Sadly, Holocaust denial has grown as survivors numbers and voices have dwindled. It's one of the reasons I wish Americans (my nation) could and would visit at least one of the concentration camps, to come face to face with what happened and with what human beings are capable of doing.
If they have such a thing in Russia, a similar visit to a camp/museum of one of Stalin's Gulags would be of similar value. Two or more (I don't know their number! Sadly ...) of my great uncles may have been swallowed by the Gulags ... or maybe the Holodomor.
Marxian or Hitlerian or ..., socialism has a consistent product, masses of innocent people slaughtered.