You got it twisted. It’s not that antifa want to “bring in subcultures that aren’t inherently anti-fascist;” it’s that antifa want to deny fascists social space or claims to subcultures that have nothing to do with them, like the three you mentioned.
We’ve seen fascists make false claims to “belonging” to subcultures and we’ve seen them grow in strength when they can claim social space within a subculture and no one challenges their claim. Think about the skinhead and black metal subcultures or football ultras – once fascists occupied positions in those subcultures unchallenged, pretty much ruined them (but shoutout to SHARP, RASH, RABM, and antifa ultras everywhere for fighting back against those fash fucknuts!).
We are 1000% in favor of people in any subculture anywhere challenging and opposing fascist, white supremacist bullshit when they try to weasel their way into those scenes.
