CoCs are one of the reasons why I choose to not contribute. I don't enjoy the risk of someone with an axe to grind to drag me into some absurd GitHub comments drama and feel justified by some generic wording on the CoC.
Not because I enjoy reading or writing hate speech or anything, but these were places that didn't tend to have any obvious problems with troublemakers, so it felt self congratulatory. And don't even get me started on the sheer amount of bikeshedding the discussions around it became, mostly from people who'd never even contributed to the project.
It suddenly made me realize there were probably more productive and less frustrating ways to spend my time.
Humans should be able to interact politely in any setting and if they don't, the issue needs to be settled with good old human interaction anyways.
Sure, but someone who went to the trouble to get their view enforced in writing is probably already a zealot I don't want to deal with.
Depends a lot on the group size, too - a few hundred contributors probably needs some rules written down. A few dozen? Not so much.