It would likely still have the same privacy issues, if people are wrongfully classified they're still going to have to turn over personally identifying information to some third party chosen by discord.
It might mean that less people have to verify their age. Guessing a users age from account activity seems unreliable. This might not be enough comply with age verification laws since there's a still a risk that they might misidentify minors as over 18.
So in places with age verification laws discord is probably continue to assume users are minors until they confirm their age. I wouldn't be surprised if discord makes the standards for "adult" behaviour really difficult to meet. Meaning this doesn't seem be for legal compliance.