From my perspective it's naked entryism, striking at the centralised weakness in an otherwise robust, decentralised system.
And then there's Wikipedias in other languages and other Wikimedia projects, which come with additional cans of worms.
It definitely happens, but the influence and uncivil behaviour by longtime editors are always, in my experience, very well disguised under a veneer of civility and lawyering. So the CoC will be completely useless against that, which is IMO the serious issue with Wikipedia right now.