I seem to remember a pretty high profile shooting which involved several antifa people attacking someone and being shot in retaliation. The trial was also very high profile and ruled in the defendant's favor that he acted in justified self defense.
Many people seem to disagree with the ruling on emotional grounds though.
Well, actually I've only witnessed one attack on a building. It was a temporary portable office at the construction site for a jail for children. So imprisoning children was the ideology ascribed to the building.
I think the view may technically be true, though of course the term "many" is very squishy. The best evidence for this is probably that (in countries with multiparty systems) you can often see surprisingly strong voter movement between the extreme parties.
That said, to think that this matters is pretty nuts. In the entire western world today, the structural environment on the extreme left is strongly opposed to the idea of campus, while on the extreme right the idea is welcomed by a critical mass.
In other words, the left polices itself. The right doesn't.