Accidents happen, especially if you've got input lag (which while I have not experienced it, many people say this game suffers from). Can't kick people for hitting teammates because it's meant to be wacky and mistakes happen, sometimes more than we'd like.
I do get your point. I made a video about it a month or so ago that I posted here. The punishment you are requesting is just too heavy handed. Some people genuinely don't care if they're you're teammate, and yeah, that sucks. But this kind of solution would punish honest mistakes more than anything else, I think.