"If you are more annoying to work with than your contributions justify, you'll be ejected." which then means that if your contributions are considered good enough you can behave like a jerk. I think I'll keep CoC's in the projects I interact with. They were created to avoid this kind of behaviour.

“Let’s make FOSS culture conform more closely to techbro culture in general.”

For large organizations, a public set of rules also provides legal cover against people who might otherwise sue/invoke the EU DSA/etc because they feel they have been unjustly banned. Also, in general, having well-articulated public rules is an honest signal of willing to put effort into maintaining a community (and also giving a hint of what that community may be like). I don't think there needs to be a one-size-fits-all solution, though.

Rules for communities are a good thing, so long as they are fair.
I.e. no rules against bigotry with caveats that "we will not act on complaints regarding reverseisms" and suchlike