Logging in and verifying age are very different. See the new account creation process for the comment you typed, as an example.

Actually this won't really affect 4chan either; while it's speculated the servers reside in California there's no critical dependency that they actually stay there, and once the physical servers leave all ties are severed with the state and California looses any reasonable way to enforce the new law.

It's kinda the same reason the site is accessible in Germany/UK/whatever despite violating every hate speech law in there jurisdiction

Are you suggesting the lack of it is a preferable alternative?

I'm suggesting that it's utterly irrelevant.