anarchism has its own history with its own principles and theoretical foundation embedded in either a historically utopian or marxian conception of capitalism
This is what I'm talking about. You don't get to say what "trve anarchism" is because you don't actually know it. Anarchism has nothing to do with Marxism, not even ancoms. They're entirely separate philosophies that view the world in different ways, both use material analysis and both stand against capitalism, but that does not mean they share a common goal, or have common ancestry. Have you actually read any anarchist theory? Or just On Authority and Anarchism or Socialism?
if a so-called anarchist advances politics that preserves capitalism
This once again proves you have no idea what you're talking about. Anti-marxist anarchists are treated as actual terrorists by the state and capitalism. They're among the most militant anti-capitalist groups on earth. The italian FAI bombs prisons while the italian ML party writes about needing critical support for ISIS in a 1998 looking ass website. Not to bring up the FARJ and the anarchists in Iran literally risking their lives as we speak. But you, from the comfort of your chair, disregard them to delude yourself into thinking what makes you comfortable.
But sure, carry on after talking to me, thinking you stand for left unity, and don't worry your pretty little head about all of these groups and people that have done more against capitalism than you or I ever have. They're not real, I assure you. They are surely just LARPing. You and the people you agree with are the one true and only based socialism bringers.
I have nothing to prove to you, and it's clear you aren't listening and just repeating all the memorized talking points ingrained inside. Believe whatever you want.