Yeah it is funny. Those people always call their books and doctrine something like ''the real teaching of the buddha'', instead of telling the truth which would make title their books like ''what I understand from the visuddhimagga and other people who copy the visuddhimagga''. THen they try really hard to match their experience with whatever is written is in the visuddhimagga and they try to match whatever is written in the visuddhimagga with whatever is written in the suttas... It gets ugly very quickly.

Mahasi is famous for that and for his huge book Manual of Insight. In this book he has half a page on your topic,

and oddly enough, he removed a little paragraph before his quote,

“And what, Ānanda, is the path, the way to the abandoning of the five lower fetters? Here, with seclusion from the acquisitions, with the abandoning of unwholesome states, with the complete tranquillization of bodily inertia, quite secluded from sensual pleasures, secluded from unwholesome states, a bhikkhu enters upon and abides in the first jhāna, which is accompanied by applied and sustained thought, with rapture and pleasure born of seclusion.

“Whatever exists therein of material form, feeling, perception, formations, and consciousness, he sees those states as impermanent, as suffering, as a disease, as a tumour, as a barb, as a calamity, as an affliction, as alien, as disintegrating, as void, as not self. He turns his mind away from those states and directs it towards the deathless element thus: ‘This is the peaceful, this is the sublime, that is, the stilling of all formations, the relinquishing of all attachments, the destruction of craving, dispassion, cessation, Nibbāna.’ If he is steady in that, he attains the destruction of the taints. But if he does not attain the destruction of the taints because of that desire for the Dhamma, that delight in the Dhamma, then with the destruction of the five lower fetters he becomes one due to reappear spontaneously in the Pure Abodes and there attain final Nibbāna without ever returning from that world. This is the path, the way to the abandoning of the five lower fetters.

This little extra paragraph just before the long one destroys the whole book by mahasi.

Their mistake leads them to confuse ''living in the present moment'' with nibanna. It is actually the classical mistake form the puthujjanas who are addicted to the senses.

Plenty of people before made this mistake, like Dzogchen, and even in the sutta people confuse jhanas with nibanna https://www.accesstoinsight.org/tipitaka/mn/mn.008.nypo.html

But with the puthujjanas like Dzogchen and the people who invented vipassana mediation, it is worse because they they identify sampajanna with satisampajanna, satisampajanna with samadhi and samadhi as awakening, whereas the people in the sutta above only confuse samadhi with nibanna.

Some people says that it is difficult to practise vipassana without samatha. I think it is about the person's experience. I started my practise after reading Eckhart Tolle's books and If anyone really investigated Tolle's teachings they will realize that Tolle is teaching mindfulness in essence and lead people to little bit mix it with Samatha-especially for the beginners. So I followed Tolle's teachings but I gradually realized that Samatha is kind of a vacation so I was predominantly practising mindfulness. After practising this way with nearly 2 years, I started to practise with the wonderful teachings of Ven. Yuttadhammo, completely leave Samatha like practises and that was perfectly doable, wonderful and that also helped me a lot.

In the beginning the practise is difficult for everyone, even you mix it with Samatha the situation is not so much different. Even that I "was" in the same category of the "mixing Vipassana with Samatha" in the beginning, I think that it is perfectly doable to just start and continue with Vipassana. Many people report positive results who starts and goes this way, many people reports that they are doing formal meditation for many hours a day this way, and I think that many or some of them-If not all-continues to practise this way in daily life after doing formal meditation. If it wasn't working, people would report that it wasn't working for them.

I think the best way to understand the root of the spiritual things is to experience them. Since Buddha gave many approaches, methodologies for the people who want to go in the direction of Nibbana, a person can't prove that Buddha only tought one or even few way to people who wants to go towards enlightenment. And with experience people would easily understand that the root/essence of Buddha's teaching is mindfulness.

Please imagine there are hundred people sitting around the Buddha, and the Buddha must choose the compatible Dhamma, Dana/Sila/Samatha/Vipassana, with the listener's habits to let the listener attain LokuttataJhana.

According to the eldest Tipitaka manual, Netti:

1. Unwholesome Habitual Person, TanhaCarita, needs to meditate Samatha to stop the present arising unwholesome because they can't control their mind arising to be just wholesome. Their unwholesome mind will arise instead of the wholesome, then the meditation will not develop uninterruptedly therefore Neyya's LokuttataJhana can't arise.
2. Wholesome Habitual Person, DitthiCarita, don't need to meditate Samatha. However, they still meditate Samatha if they still have enough lifetime to meditate it. However, for the wholesome Habitual Person who has not much left lifetime, the Buddha will let him meditate only Vipassana, without Samatha.

For the unwholesome habitual person, he can meditate pure Vipassana, but its risk for him to die before he attains LokuttaraJhana because it is harder, almost impossible, to attain LokuttaraJhana around unwholesome arising.

What is wholesome meditation?

In short, an attainment/enlightenment (of both LokiyaJhana and LokuttaraJhana) is a graduating moment of wholesome mind development/meditation, so if some passion, unwholesome mind, still able to arise and interrupt the meditation, it can not be called "attainment/enlightenment".

In detail, a wholesome mind arises without any passion and causes at least the present and future resultants. In LokuttaraJhana context, wholesome mind causes of attaining the cessation of all sufferings as well. The 30-36 wholesome factors have to arise together with each mind moment depend on the compatibility with the environment and situation. The arising of wholesome mind moment will interrupt an arising of the unwholesome mind moment because the mind can arise only one per time (but it arises super fast more than a trillion times per second), so wholesome arising without unwholesome and wholesome arising without unwholesome.

All kinds of meditation are developing above wholesome mind to arise continuously uninterruptedly.

The Freshy Vipassana, TarunaVipassana, still has unwholesome minds, passion, arising around the present wholesome mind arising.

The proficient Vipassana, BalavaVipassana, has only wholesome minds arising for a long time continuously uninterruptedly without any passion, unwholesome.

The graduating Vipassana, AriyaMagga, is the perfectly completely ceasing moment of the passions by the powerful enough BalavaVipassana. The graduating Samatha can stop only present unwholesome mind arising but the The graduating Vipassana can let the passions ceased forever.

The attainment/enlightenment (of both LokiyaJhana and LokuttaraJhana) is a graduating moment of wholesome mind development/meditation, so if some passion, unwholesome mind, still able to arise and interrupt the meditation, it can not be called "attainment/enlightenment".

If one say Netti or Tipitaka conflict each other, it means that one doesn't know the right way to deconflict their misunderstood, wrong reading, by a lot of evidence, supporting each others. It doesn't mean Tipitaka or Netti actually conflict each other.

The Dhammapada says:

372. There is no meditative concentration for him who lacks insight, and no insight for him who lacks meditative concentration. He in whom are found both meditative concentration and insight, indeed, is close to Nibbana.

There are at least two suttas (AN 4.94 & AN 10.54) that refer to vipassana without samatha. However, personally, I don't believe them. Suttas such as the 2nd sermon (SN 22.59) & the Anapanasati Sutta (MN 118) say the seeing of impermanence, unsatisfactoriness & not-self results in dispassion (viraga). Therefore, if the mind has dispassion (viraga), obviously it must also have tranquility (samatha); because "viraga" means "without lust". Further, those suttas also say dispassion (viraga) results in nirodha (cessation). It follows having true vipassana without samatha appears impossible.