99.9% of vehicle drivers are safe and considerate judging by my experiences. Critical mass type protests disrupt the journeys of these drivers as well as the idiots we all want to educate.
Imagine the vulnerable elderly individual (maybe they used to be a keen cyclist),waiting for their home care worker who they rely on for food and the drugs they need just to manage their pain. Sadly the care worker (also a keen cyclist) is going to be an hour late because they are stuck in a traffic jam caused by a mass of militant cyclists.
Perhaps over emotive, but all the same critical mass type protests will only result in a more entrenched attitude of us and them, even turning some people violently against cyclists.