The real point is matching people to hardware to enforce onerous anti piracy measures, anti ad block measure, and anti-"Sorry citizen you are not allowed to discuss taboo subjects like gay people and Socialism" measures. Also long term probably some "why are you usng your technology during the daily prayer hour citizen, please report to the reeducation camps.

If the OS allows you to setup user's age during the out of box experience and then locks it a parent would only need to partake in that step. Other applications and sites that require to check age could then receive a simple Adult=true or Adult=false and make sure to send those with the Adult=false to the 403 forbidden to jerk off page.
Kids would then learn man in the middle attacks to modify the flag before it is sent to the application.
So the point is to improve computer literacy, I think?

Microsoft Word won't let you use the word 'dick' in your essay if you're under 18, even if you were writing about the (not so) good old Richard Nixon. And Excel won't let you add up to 69 either, math can be so naughty!

Think of the children!