> I think argument for seatbelts is that there is minimum disruption to usage, there is limited revocation of other rights, and the societal benefit is large and pretty unambiguous.

Said like this, it looks to me that it has a parallel with social media.

> The idea that I have to give up privacy

You don't have to, though.

> expose myself to additional risk (by having my identity logged)

It doesn't have to be, we can have privacy-preserving age verification. Now we could discuss the specific implementation, but in general that's feasible.

> increase the chances that mentally susceptible people will have more exposure to fraud

It's not enough to say it: is it actually the case? You can already get phished by trying to access a social network, how does that make it worse? I don't think it's obvious. While the problem with kids and social media is, at this point, very well documented.

> if not an out right straw man.

I, for one, think it's an interesting experiment. All the arguments above could be used against making cigarettes illegal for children. Yet I am very convinced that making cigarettes illegal for children is the right choice.