I'd be interested to know how it could be a good thing.
I'm all for shutting down Facebook entirely and jailing their executives, but i don't think age verification is an appropriate answer. It's already common at least here in France for Facebook to request user ID cards (wtf) and that has not at all stopped harassment, nazism, fake news, etc...
Are you talking about the goal being bad, or the methods being bad, or that the goal inherently cannot be achieved without bad methods?
E.g. I think something pretty uncontroversial would be a goal of blocking kids from the likes of TikTok & Instagram between 22:00 and 08:00.[1] But if I'm an adult, that's a different matter. Ok, so how do I prove I'm an adult, without society turning into a surveillance state, or surveillance capitalism?
Next up: wouldn't it be nice if e.g. someone over the age of 30 couldn't initiate chats (including comments on posts) with 13 year olds? For hobby exceptions (e.g. joining a computer or chess club) it would make sense to either have parental approval, or some moderation requirements for parental approval exempt groups.
[1] I'm here not saying that this is the biggest problem, but it should at least be uncontroversial.
What age verification has to do with stopping fake news or harassment?