In the real world people make practical decisions that mostly end up relating to kicking out assholes rather than political differences.
When I talk about anarchists not being able to agree on what makes someone an anarchist I do so from a place of affection as I was active in anarchist or at least anarchist-positive organizations in university. When I see libertarians saying, “well, that person isn’t a real libertarian” I see it as a little ironic, but I also cut them a lot of slack because I recognize where it’s coming from.
I don’t cut them any slack on anything else.