alt Hacker NewsOr alternatively - you could recognize that normal people are getting more and more pissed off by the fact that social media companies are force-feeding garbage into their kids eyeballs 16 hours a day.
We could give them a reasonable solution that demonstrably preserves privacy and doesn't inconvenience anyone else (Suppose you want to see all the uncensored everything, you open your new PC or phone and say your DOB is 1/1/1900. Done. Status quo.)
Or we could be alarmist about that, torpedo that plan, and then in 2 more years when people are even MORE pissed, a horrifying new plan comes out, where the government scans your photo ID (with the help of some crappy private contractor of course) and both of them promise to probably not store the info and log your access. And that one manages to scrape by because people are at that point even more pissed and are determined to solve the problem somehow.
The actual 'bad guys' just wouldn't be able to get the public support for that second, shitty plan, if we basically solve the problem now with this very modest plan that's on the table now. Parents can handle this simple one-time out-of-box prompt and it makes sense. Device owner, the parent, that's the one who should make the call.
I actually agree with you, but you have an optimism about the ability for open source maintainers to have achievable political aims, in a way that I haven't seen happen for decades.
What your happier future looks like requires both a technical solution, but more importantly political wins to sell that solution as the better one.
The current operating systems weighted by users, are entirely under the control of three major players, who are incentivised to further centralise things.
( I'm counting the three operating systems as Google Play Services, IOS and Windows. Yes, AOSP exists, but it's useless without Google Play Services. ).
I also don't think a device level switch would stop anything for a second, given the number of stories of parents who seem to hand their children their credit card, then complain about them racking up thousands of dollars on Roblox or whatever.
When the light-touch measures fail, the framework will be leveraged to start requiring more centralised and less private solutions.