Someone came up with a good theory a while ago that I'm inclined to believe: The social media companies (esp. Meta as I understand it) were looking at huge fines for showing adult content to under-18s, so they lobbied hard to ensure that the burden of proof for age verification was on anyone else but themselves, hence why the OS vendors are being targeted now.

Ultimately, they seem to have realised that they can't stop adult content from being shared, so the easiest way to get there was to mark anything even vaguely possible of being adult, and require age verification -- which comes with a lot of political cover vs. just deleting it.

Of course, if you stoke up the right people, you end up with lots of support from the puritanical brigades, and label all naysayers as putting children in harm's way.