This is just a backdoor way to tie real names to online accounts.
Someone think of the children! /s
So, show me a photo of your driver’s licence to prove you aren’t one.
Most of the Internet denizens who identify as juvenile (or act in a juvenile manner) are actually legal adults. Meanwhile, legal children who are in difficult situations may not have access to the support they need.
I believe that legislating when someone is considered mature does not account for the outliers who are the ones who would benefit most from access, or having their access restricted.