

The post was directed towards communists, I didn’t expect it to reach non-communists, but nevertheless I’ll answer your questions:
I’m not sure I follow the logic here.
Requires a bit of context, but essentially what I’m saying in that paragraph is that this fear of Stalin and previous socialist experiments leads people to follow nominally socialist ideologies that don’t lead to revolution. Examples include anarchism, libertarian socialism, Trotskyism, democratic socialism, vague Marxism, and on the off-chance small niche ideologies that a dozen people believe. It’s not my fault that our predecessors who achieved proletarian revolution had respect for Stalin.
Wouldn’t it be better to then blame it all on Stalin?
Putting all the errors of the USSR on the individual of Stalin is not Marxist, it’s practically great man theory. Decisions were carried out by the party, not by a single individual. That being said, it’s not wrong to blame Stalin and his administration for their real errors.
It’s a lost cause from how well publicized Stalin’s crimes are so rather contraproductive to recruit people
That’s what we call opportunism; short term gains, long term problems. Communists should stand firm on their principles and drag the world leftwards. Changing the narrative is not a lost cause, if it was then may as well abandon communism because most people have been have a hatred towards it.
On the topic of recruiting, if Stalin turns off people from joining Marxist-Leninist organizations, good. We don’t need non-Marxist-Leninists in Marxist-Leninist organizations. non-MLs do have a place though, they can join left mass organizations. There’s also no issue with MLs working with non-MLs, they just don’t belong in an ML organization.
it requires to whitewash history and suppress history
It does require us to deny the claims of cold war pseudo-historians, yes. Such as Robert Conquest, who was affiliated with the Information Research Department, a secret propaganda department of the government of the United Kingdom during the cold war. Not all cold war sovietologists are as egregious as doing the work of a secret propaganda department, but there certainly was an incentive to write pure nonsense. The more negative you wrote, the higher the chance you’d get propelled to the higher echelon of prestige.
it prevents addressing questions on how and who accumulates power, how candidates are filtered and advance towards ultimate power and how to prevent for example sociopaths from claiming ultimate power
Doesn’t any modern communist theory HAVE to include ideas of how to prevent someone like Stalin from gaining power?
Not the right question to ask from a Marxist perspective, as its not the individual of Stalin that matters but the party as a whole. Marxism is in complete contradiction with great man theory; systems are what matters in this world, not individuals. The question should be, “How do we prevent the party from betraying the revolution?”
This is a topic of great importance, as the greatest threat to the revolution are internal as proven by history. Stalin’s solution was the great purge, in my opinion this was not right, it didn’t prevent or even delay the USSR from reversing course to capitalism because it didn’t deal with any root issues but only the surface manifestation. Trotsky’s approach was the permanent revolution, this was also not right as it hinged on Trotsky’s disbelief of the revolutionary potential of the peasantry. Mao and Hoxha’s approach was cultural revolution, though sharing the name had different approach with Mao’s being bottom-up and Hoxha’s being more top-down.
Again, these are the names of the leaders but in truth were the attempts of their respective revolutions to tackle this issue.

In truth, I really do hate speaking on this topic. I really don’t like handwaving human lives like this. The only reason I do this is because it makes people think communism is a force of evil worse than fascism; a sentiment that keeps the bourgeoisie in power, because the alternative is apparently so monstrous that the plunder and impoverishment of the global south, the eternal wars of the world, the destruction of the ecosystem, and the continuation of wage slavery are so so much better.
The vast majority of gulag deaths happened in World War 2 when the supply chains broke down, causing many people to starve.
Indeed those people who died in the great purge weren’t all “too dangerous to be left alive”, the great purge went completely out of hand, there’s no consolation I can give on this topic; some people put the blame entirely on Yezhov, because the VAST majority of deaths happened during Yezhov’s leadership of the NKVD, but again putting blame on individuals like this is not Marxist, it was the fault of the party and the system as a whole at the end of the day.
On deportations, I can’t speak on that or if those numbers are accurate. But think about what “deported during the 1940s” actually means, it means deporting people during World War 2, during the German invasion.
Also, you kind of skipped the next sentence of the Wikipedia article
Why can’t I just say Stalin was a fascist or a traitor like most ‘respectable’ communists in the modern day? Because it just feeds in to a different liberal criticism of communism, which is that it always leads to dictatorship; I don’t accept that premise and you shouldn’t either. The Marxist conception is dictatorship of a class not individual dictatorship, even his biggest hater Trotsky didn’t take Stalin as an individual dictator, but as the reflection of a degenerated worker’s state (though I also don’t accept this either as this is derived from Trotsky’s distrust of the Peasant class). Stalin was a true communist. I suggest you read some of Stalin’s writings, I’ve read quite a bit of them and there’s not that much I disagree with, I don’t think you’d disagree much either as a communist.
I’m obliged to say thought that Stalin is not nearly as important to Marxist theory as Marx, Engels, Lenin, or Mao as he hardly made new additions. But the possibility of Socialism in One Country as formulated by Stalin is to be upholded. In truth, I’m completely fine with people being critical of Stalin as long as they uphold his line (I’m also not posing Stalin’s USSR as sunshine and rainbows as you can tell), but usually people who hate Stalin follow deviationist ideologies like Titoism, Trotskyism, etcetera, etcetera and that’s the core of the original post.