"...And in the end it worked."

While I have an idea of what you mean, I'd reexamine that conclusion. It worked for a while. IMO, the Soviet system wasn't sustainable until Khrushchev - Beria and Stalin were constantly trying to figure out when the other was going to murder them.

I think the pathology in play for Lenin and Stalin was akin to eliminationism on a smaller scale - once someone became "othered", they were pretty much destined for one behind the ear.