[dude with glasses in a communist t-shirt, arguing] I'm the only leftist here, your opinions are TRASH
[dude holding a theory book on smug, arguing] Read theory you losers, you're all WRONG
[dude in an anarchist hoodie, arguing] Nuh-uh, I'm the only leftist here, you're SHITLIBS
[the three dudes are now caught in a cartoon fight, glasses gone flying, punches everywhere, while a firing squad of nazis are targeting them with rifles]
[a confused nazi asks] Why… why are they still arguing?
It's a similar to MAGA in a way. MAGA's biggest problem, as an ideology, is that it revolves around blind loyalty to a single idiot and therefore the entire movement starts and stops with his whims, no matter how contradictory, damaging, or nonsensical. You could say it's confirmation bias that I have this opinion, but I think given recent events, this opinion does have a basis of fact to it. The same applies to the left when it comes to purity testing. It's really not hard to see how prominent purity testing is in leftist discourse.
That's not what I'm asking, I'm saying you can't judge now many people are not engaging in purity testing.
That's exactly what confirmation bias is. "All the toupees I see are bad, therefore, all toupees are bad." Confirmation bias with a basis of fact to it, still completely ignoring the toupees you don't notice.