That's a bit ridiculous, with respect to the Marx claim. Marx was attacking Dogmatism, not his own ideas. Post-Marx's death, people following his ideas understandably called themselves Marxists not because they worshipped Marx, but because they were working with his ideas!
As for Bakunin, he's a pure idealist here. His rejection of the state is based on the notion that the elected cannot represent the will of the people because they are not the people. This, of course, is wrong, as it assumes the people do not want someone managing higher-order decisions! Letting vast improvements in material conditions be held back because workers had representatives is why Anarchism has failed to last very long.
As for the USSR being "State Capitalist," that referred to the NEP. Judging Leftist movements by their structure as compared to perfect Marxism in a vacuum without considering the historical context is deeply silly idealism. You would have to do some heavy justification for why you believe a worker state to form a new class that isn't just vibes.