Two points:
1) It's true that there were uniquely powerful and dominant figures during both the Red Terror and the Collectivization. But those were people who genuinely had the support of the rest of the Party. Many of the other Bolshevik leaders were just as bad. In fact, Trotsky (the alternative on hand who usually plays the "if only the czar knew!" role to wishful leftists) was if anything worse, pushing for an immediate campaign of massive warfare and terrorism to be extended to other countries and being particularly brutal in putting down rebellions.
2) Thinkers trade in abstractions--thought is really just the application and generation of new abstractions. It's not clear to me that you can hold those thinkers responsible, though, when people proclaiming their ideology use their abstractions to ride roughshod over human rights (itself an abstraction...)
Take Adam Smith, who's a secular saint in the Anglosphere. The liberal version of British imperialism embraced him and laissez-faire capitalism to justify actions that cost tens of millions of lives. E.g. the Irish famine, the Indian famines, arguably even the Opium Wars/Taiping Rebellion. A typical argument for not providing famine relief by the Indian Famine Commission:
The doctrine that in time of famine the poor are entitled to demand relief [...] would probably lead to the doctrine that they are entitled to such relief at all times, and thus the foundation would be laid of a system of general poor relief, which we cannot contemplate without serious apprehension.
This variant of capitalist ideology was the deadliest in the world during its time, until variants of Marxism managed to blow that record away. I think you can just as easily say, "A philosophy that reifies an amorphous abstract idea like property rights to the extent that people's lives don't matter if they lack property is extremely disturbing."
It seems to me that the only ideologies out there with clean hands are the ones that only exist in people's heads.
FTR, I think the healthiest approach is to reject all ideologies that pretend to be all-encompassing and use the analytical tools provided by them as needed. Epistemological, if not political, anarchism.