Worst control M i ever experienced was a cav jumping over a wall into my over head swing at an enemy.
Ctrl M is shorthand for, "Dude! Seriously, fuck right off!"
It should only be used for HA, range that is shooting into five friendlies trying to get the one enemy they are ganking, cav that is too lazy or drunk to steer, jerks who kick/push range when they are aiming, and noobs that hit you three times in a row. Sometimes it makes them check their swings. Sometimes.
You should not report a ranged when you are surrounded by ten enemies and he still manages to headshot you. You should not report a cav when you are surrounded by ten enemies and he manages to couch you and not even horse bump a single enemy. These are game glitches, and most experienced range/cav know that there is a 90% chance of killing a teammate if they try to save them.
And report guys who punch at the beginning of the round. Its just annoying, and i can't see the humour (too old I guess).