There is passive anti fascism and active anti fascism. That’s the point here. Most people are passively anti fascist. At different points different people will be driven towards becoming actively anti fascist. For me it was the echoes of Charlottesville and the kkk marching near my home.
Fascism is the most extreme anti human stance. Active anti fascism is noble rather than extreme. It is noble like feeding the hungry. Everyone should be able to agree that it is the right thing to do, and we should be proud of all who do it, but it can be difficult and inconvenient or any number of other things can get in the way rather than it being “too extreme”. And in fact plenty of non radical people do celebrate acts of anti fascist action in our modern era. That gif of Richard Spencer being punched is something most folks lack the courage to do but can acknowledge that it’s right and good.
The hit on antifa is a specific disinformation campaign by right wing media. It’s akin to their attacks on blm. Trying to portray loose resistance to fascist organizing as the left wing equivalent to the proud boys instead of just normal people opposing fascists and deciding to make that opposition material.