@markvonwahlde as someone who used to subscribe to this nonsense take: the true history of antifascism involves physical resistance as part of a diversity of tactics, e.g. see Dave Hann's book of that name https://www.goodreads.com/book/show/17221692-physical-resistance
As to why this is, consider how effective fascists are at presenting themselves as providing safety if they lose streetfights, and how much physical harm they're able to cause when not resisted (e.g. look at the EDL in Luton in the UK in 2011) - especially given the police collaboration that you currently point out.