Why are people so riled up about them? Antifa's bad, but they're not neo-nazis. They're a disorganized rabble whose whole shtick is being anti-fascist. Yeah, their definition of fascist is flaky and they cause trouble, but AFAIK they haven't killed anyone, and the militant left has basically been dead for decades.
Compare that to neo-nazis and white supremacists, who think Jews and non-whites are subhuman and who have a
long history of actual murders in the US. There's decades of white supremacist hate to feed off, and a clear history of violence by the far right that antifa can't match.
Sure Antifa needs to be denounced, but let's be real, the actual Nazis and white supremacists are worse.