Ehhhh. The stage was set by the time Stalin died for revisionists to take over. It would have likely taken another revolution to fix the problems with the USSR at that point. Don't want revisionists in your party? Don't murder all the ones that stick true to Marxist-Leninist thought

But he only got rid of the tiny little proportion of the population who opposed the entire proletariat mass. He killed a tiny portion of revisionists and people who wouldn't follow marxism-leninism for the proletariat, for the benefit of the entire oppressed peoples, to build communism, to try, as hard as possible to build a communist, classless society. Thats a tradedoff that any Marxist-Leninist should be willing to make for the benefit of everyone, all the masses. You fixate on these tiny little groups, who were oppressed for the benefit of the majority, for the proletariat, everyone basically. Side with the majority always, thats the Marxist-Leninist science. Life under stalin was fucking great for the majority of the peoples compared to before, the tsarist, feudal society, anything else is revisionism.

objectively great compared to any other leader

Eeeehhhhhhhh...... That's a bit of a stretch.

Like who else?

It wasnt. Not by a long shot. And it arguably wasn't even socialist (see: Lenin "this shit is state capitalism and its fuckin up")

It's liberal lies, all of it. Almost no-one who lived in the USSR under stalin disliked living there, it was pretty good by the end, after the purges and the rebuilding and massive industrialising from a shatered economy of mostly peasents slaving in the fields, with people starving in the streets to an industrial powerhouse rival to germany, the UK, the USA, its incredable, so fast, so wow, things were just great, how did they do it? Wow. If only they hadn't had to go and defeat the nazis for the liberals, things would have skyrocketed into greatness even faster than they did, maybe we'd be living in FULLCOMMUNISM now if that had happened, if fascism had been defeated faster, its worth an analysis. Thats the power of socialism. Thats the power of marxism-leninism.

All this while being feared across the world, the capitalists saw their own executioners, working amoung them, their own proles, they were fucking terrifying, the bourgies of the other countries were like fuuuuuuuuck, these proles are like not only just going to kill us, but they do do things better when they work under communism, better step our game up, doe everythign we can to discredit them, they even supported hitler, a fascist, a capitalist gone mad, hacking at the feet of the societal pyramid, in the hope he would defeat the uppity proles in the USSR

And thats why I love stalin