The problem is that age verification quickly becomes a method to justify the mass policing/data scraping of your player base. I for one don't want to play a game that insists that I need to connect my government identity to the game to play, not in the sense that the players know it, but that, for example, VRChat has it.
I talked to a veteran player who has been playing VRChat for seven years now and knows most of the staff/the community manager before he became the community manager. She said that VRChat has struggled with data leaks since its inception, including leaking government IDs. Apparently the community manager is a creep and only got his position because he saved the app a while back by donating loads of money. Imagining that guy has moderation permissions because he cash-cowed and now has access to thousands of government IDs is unsettling to say the least.
This isn't to say that they shouldn't age-gate the whole thing. Most privacy sensitive people will simply choose to not play, which honestly isn't a huge concern, and the benefits definitely outweigh the negatives here. After being witness to this stuff for a while, truly the best solution is to educate parents on their children's internet behavior and encourage bad actors who involve themselves with minors "because it's the internet and it's bound to happen" to fuck off and get a life.