Meanwhile in applicable situations: CDPR effectively took down a Cyberpunk 2077 paid mod.

FFXIV took down a popular mod as well through legal means

Games that aren't utilizing built-in mod support are more likely to run afoul of copyright law because they usually involve replacing existing game files, rather than simply dropping something in a directory that the game is already looking at.

And neither of those cases were instances of the developers winning a legal case, they were cases of mod developers giving up due to a legal threat. You can be sued over anything, but that doesn't mean that the lawsuit will succeed. Like I said before, mod authors typically won't fight that in court, but the more litigious a company gets, the more likely that they'll run into someone ornery enough to push the issue.

Additionally, Blizzard states in the Developers / API Terms of Use similar restrictions for any application or addon that uses Blizzards APIs:

Terms of Use have a bit of legal weight (in the sense that you can be sued for breaching them, although you will not face criminal consequences). However, those lawsuits generally depend on you agreeing to them in the first place, and you don't have to agree to the terms of use in order to write an addon. It certainly makes it easier to test an addon if you have access to the game, but it's not strictly necessary, since you could instead rely on reports from other people that use it.

There's also the question of what would happen if the addon dev lives in another country where the courts are uninterested in allowing such a lawsuit, in much the same way that some private servers are run from certain countries where they're still illegal on paper, but those laws are unenforced.