> This is amusing, because the usual NIMBY argument I hear is about "gentrification", i.e. it makes the neighborhood better and that's bad.

Change is bad as far as existing residents are concerned, which is why external YIMBYs are particularly annoying. I live in a pretty nice area so gentrification isn't really possible, and the people who want to live there but can't afford to are the ones agitating for change.

> More accurately: they would like to live in a particular location, the owner of that location would like to sell or rent it to them, but a third party wants to forcibly prevent that transaction.

No, the accurate description in CA (and YIMBYs are trying to replicate this elsewhere) is that a group of people collectively decided how land can be used in their area, and people who disagree are going over their head to change the rules.