I'm not making the case that Marxism had good ideas here, I'm making the case that Marxism had ideas that led to change in the direction it seems, without collapse, in the places where actual Marxism is a thing, and that the collapsed systems that called themselves Marxist shared a common deviation from Marxism on fundamental points stemming from their shared point of departure, Leninism.

Also, treating Marxism the way you suggest empowers the people who will use association with Marxism (which whether or not people who think Marxism had good ideas avoid the name, people who don't can still draw the connections) as an attack against an idea, leveraging the failure of Leninist societies to suggest that anything associated with Marxism is bad. So, no, I'll continue to point out that that involves not only the ad hominem fallacy, but also the fallacy of equivocation.