The problem with the different opinions of what CM is that it only takes one person to transform the ride from a celebration into a protest. 49 people could peacefully ride around the city (clogging traffic or not) but if one person decided to swing a u-lock at a driver or pedestrian, it’s all over–that single action could do more to hurt the way the public views cyclists, and undo the effects of a dozen positive CMs.
I’m not suggesting, however, throwing the baby out with the bath water. If or when something “bad” happens at CM, the participants should police themselves. Just because CM isn’t an organization doesn’t mean that well-meaning folks should allow it to be hijacked by someone looking for trouble.
By the way, I believe according to PA bike guide, it’s recommended that bikes ride no more than 2 abreast on the road. While CM generally breaks this suggestion, riding 2 abreast will clog the lane anyway.