It starts with that and gets out of hand. If the police did not wade in, none of that would have happened. BLM would have just marched. When the cops tore down the barriers lots of criminals and kids saw a chance to raise hell. When the police did not act violently, the demonstrations were boring.
I marched in the civil rights demonstrations in the 60s. We were aware that it would go nicely unless the cops waded in, then all hell would break loose. There were always violent right-wing groups that screamed and threatened the demonstrators. If it went peacefully, the people had to get back to their cars without right wing haters attacking them.
I know none of us wanted violence because it was almost all one sided.