Acting like antifa is not a modern movement that subscribes to an ideology and is something that is just to be expected of a good member of society is why people are easily convinced of the fascists attacks on the idea under that name and enables the messaging of the movement to be handwaved or persecuted.

Acting like it is makes its own motivations seem like those deemed by a collective and not individuals making their own minds to decide for themselves (and gives the ICEstapo something to target). If a large number of people see something as fascist, it doesn't make them 'members of antifa', if anything, they just have a concience and common sense. What's the old addadge. "Reality has a leftist bias?"

But that's all we're both doing for our own headcanons, isn't it? 'Acting'. Neither you or I can speak on what antifa is for everyone claiming it. It doesn't even represent its own manifesto to question, so it feels a bit irresponsible and ego-driven to deem a purpose for it when we're just two raindrops in antifa's gutter, leaderless and self-enlisted.