showing you are failing to seperate the ideology from real world groups

There is no separation.

Groups practicing Marxism fail because Marxism is a failed concept.

If you had some example of Marxism succeeding maybe you'd have an argument, but you don't & you don't have an example of Marxism succeeding, for the same reason history has no example of a society functioning on the concept of "eating only Styrofoam."

You don't get to sit there & try to separate the ideology of eating only Styrofoam, from the action of eating only Styrofoam. It's a fatally flawed concept, it is flawed, you can't make it not flawed, it's very nature makes it non functional.

Fatally flawed systems will always fail when tried in the real world, by their very nature they are flawed, fatally. They are ideologies that do not work & there is no way to make them work.