Upvote:2
When is it safe to assume that the UK visa process is what it claims to be?
Immediately.
If it says something on a UK government website such as https://www.gov.uk/government/publications/visitor-visa-guide-to-supporting-documents you should absolutely proceed on the assumption it is true.
If it turns out not to be true (due to e.g. error on their part) you almost certainly have cause for redress.