What?
Regarding ideology, it doesn't matter much. Look behind the rhetoric. Look for the motive. Why did Stalin promote Lysenkoism? (I just glanced at the Wikipedia notes on this, feel free to chime in with an authoritative source.) Better question, why did Stalin purge so many people? And how might that be accomplished?
When you're the leader of a modern country -- not just a tribe, or village, but millions of people -- you don't have the courtesy to deal with individual actors, for better or for worse as the case may be. If a lot of your opponents are coming out of one geographical area, say, you'll be more than willing to sacrifice a few of your supporters -- they'll go quietly, in support of your cause, after all -- by, say, changing a few convenient rules affecting that area, or its demographics or zoning or what have you.
This is well outside the domain of ethics, or psychology. This is just pure, cold, hard power dynamics.
The only thing the ideology does is make people easier to manage.
We might wish that the values give rise to the actions, and we might wish that those values in turn arose from a moral or theological system: something better than ourselves, that we can trust, and which facilitates participation in a society: a system of common traditions. But in fact, it works the opposite way. Value systems themselves may arise in a natural way (evolving through incremental changes, mashing up different ideas, and original creation), but their promotion and legitimization only follows the distribution of power.
This is why the "values-actions gap" is a thing.
I wonder if any polisci people have quantified the values-actions gap. I would be willing to bet, if you plot it versus wealth inequality, the correlation is quite strong.
Tim