The real problem is US (and English common law generally) don't have good ways of prosecuting groups for group crimes. We generally attribute crime to the individual, and in fact there are laws against
collective punishment, even in international law and the Geneva Conventions.
So if a group of 20 idiots impede a police operation, we can't round up all 20 and charge them with 1 crime. We have to say that 1 was attacking a cop, and 1 was standing in front of the car, and 2 were resisting arrest, and 3 were flailing around yelling and getting in the way, and the other 13 stood on the sidewalk or let someone who was fleeing hide behind them, etc. Of those 20 only the attack and resisting are specific crimes, the other 17 can get off the hook by saying they were just standing around or shouting protected speech.
Everyone
knows the entire crowd of 20 assholes were coordinating and working together to make the cops' job impossible, but you can't prove it to the legal standard. Even if you tried one of the few conspiracy statutes on the books, you would have to prove specific things like "Jane wrote in an email that she would provide cover for anyone attacking cops and fleeing, then she did exactly that on the day of the protest. It only looks like she's innocently standing with a sign."
I know a lot else happened since then, but I continue to be disappointed nobody passed laws to hold organized groups liable for street actions. Everyone knows about affinity groups and coordination, nobody managed to get a legal tool to fight them.