Problem is that most if not all (online) tankies have only a very limited, sketchy idea of what those actually are.
Another problem is that you list ideologies, i.e. somewhat theoretical stuff, but how does that relate to the actual atrocities? I don't think Stalinism says "go and kill millions of dissidents".
Isn't that the main problem with tankies, that they defend indefensible tyrannies because to them they are identical to the ideologies?