Simple attestation is very useful for the case where a parent gives a child access to a computer and wants that computer to block porn. That's the use case everyone is clamoring for, and asking the root user "how old is this user?" solves it in a simple, open, privacy-preserving way. Everybody wins, except the teenager who wants to watch porn. If this were not legally mandated, everyone would support it as a useful feature, but since it is legally mandated, we have to get angry about it.
This has got very little to do with children - that is just the excuse that sounds good. "Think of the children" is a rhetorical tactic that anyone who wants to get unfettered access to your data rolls out whenever they can. It is a tactic that unreasonable people use to influence reasonable people, because it is so difficult for a reasonable person to argue against without coming across as uncaring and/or bigoted.
If it was an excuse to get your data there would be some data-getting involved. It may be hard for you to believe, but lots of people really do want parental controls that actually work and are bound by the force of law.
Yes that may be true, but parents are being misguided by efforts that are trying to control aspects of data.
If you, as a parent, make yourself open to this attack, you will find that you are making us less free of a society by expecting others to parent for you.