score:1
One part of why Stalin was so brutal may also come from Russian history and outside forces. To this day, one of the reasons Russia expands its territory and contends with such a autocratic government is to protect itself from Western control and intervention. There was the Great Game, a proto-Cold War where the United Kingdom tried to use India to spread its influence to the territories neighboring Afghanistan and Russia, the French invasion of Russia in 1812, and the attack by the German Empire during World War I. Stalin, like many other Russians before and post-World War II, was obsessed with protecting Russia from any perceived future invasions by the West and establishing other Marxist-Leninist states to protect the Soviet Union. Stalin learned of Marxism from reading various sources and establish a particular version of socialism/lower stage communism I wrote about previously: a 'dictatorship of the proletariat' like what Karl Marx wrote about in his work Critique of the Gotha Program.
He established a command economy when the New Economic Policy implemented policy temporarily established a market economy not only because it is part of Marxist socialism, but because it would be able to protect the USSR from being affected by the market economy of Western capitalist nations. Stalin even saw a foreigner threat from other non-Marxist socialists, calling them "social fascists" and calling those who stood in the way of the dictatorship of the proletariat corporatists. To Stalin, these groups were strengthening capitalist nations like the United States and preventing proletariat revolutions that would lead to socialism, and eventually the final stage of communism.
Stalin also believed that if the dictatorship of the proletariat released its grip too soon if the face of the capitalist West, they would "end up being controlled by the most reactionary elements of their community", returning right back to capitalism & a market economy that would make Russia a puppet of foreign forces.
tl;dr Stalin's brutality was somewhat based on a logic that the dictatorship of the proletariat was the true method to Communism and that he was surrounded by enemies β enemies who wanted Russia to turn to capitalism. Russia had to deal with invasion and interference from Western nations before, so Stalin β to some degree β saw his brutality as a counterbalance and a way to purge those who were seen as too subservient to Westerners (and by extension, capitalism).
Update: As someone pointed out in the comments, the Great Game wasn't entirely one-sided and Russia was also imperialistic to its neighbors during that time. However, from the Russian perspective, their actions were a necessary move to prevent Great Britain from controlling their neighbors and - by extension- indirectly influencing Russian policy. Meanwhile, the British -thanks to somewhat exaggerated accounts and reports - believed they needed to control Central Asia and influence Russia because Russia was planning to control India, something Russia had no intention of doing. My point was that this feeling that western powers like Britain were planning to control Russia & that having neighbors aligned with Russia could help to protect the nation's autonomy is a concept that stretches to before the existence of the USSR & influenced Stalin's attitudes.
Upvote:14
Summary:
Don't confuse cause and effect - Stalin succeeded because he was the most brutal and ruthless Politburo member. Only someone even more brutal and ruthless could have succeeded in his place.
The certainty of dogmatic fanaticism requires no further justification; as it justifies itself.
.... Stalin, as Kotkin reveals him, was neither a dull bureaucrat nor an outlaw but a man shaped by rigid adherence to a puritanical doctrine. His violence was not the product of his subconscious but of the Bolshevik engagement with Marxist-Leninist ideology.
This ideology offered stalin a deep sense of certainty in the face of political and economic setbacks.
Stalin saw obstacles in his way, and removed them with whatever degree of force appeared necessary at the time. When the only possible direction is forward, no opposition can be tolerated.
Whatever went wrong, the counterrevolution, the forces of conservatism, the secret influence of the bourgeoisie could always be held responsible. .... Over and over again, Stalin learned that violence was the key to success. ....
But if he was sufficiently ruthless, all opposition ultimately melted away. ....
Stalin wasn't a dreamer like Lenin or Trotsky, which is precisely why he accepted the position of General Secretary of the Party; why the others were content to let him have the position; and why he ultimately proved to be master of them all. Stalin was the diligent, conscientious bureaucrat who plumbed the depths of the party organization for supporters; and always turned up with far more supporters than anticipated at every crisis of leadership.
All quotes from the article quoted in the original question.