> People might've been interested in helping to counteract the effects or sources of a problem if a change advocate approached them in a manner that was constructive, achievable, rational, and considerate.

I mean this is just obviously and flagrantly untrue, eg. Greta Thunberg became a culture war boogeyman for half of the political spectrum over significantly more moderate views expressed in exactly the way you describe. If anything, acting like a bitch just emboldens the type who cause problems to cause more problems when they see these signs of weakness and zero will to resist them, as we see happening with acts of complete irrationality like Trump making a war against fucking wind turbines a top priority of the US government's agenda.

When you tell people they're protesting the wrong way, you're really just saying "I don't want to hear your complaints. Make them in a way that doesn't bother me so I can ignore them".