I agree with you that changing the behaviour of the networks would be better, but what actions does a state like Australia really have here?

If they just say, "change", it must be backed up by a threat -- "we will fine you" or "we will ban you" are, I think, the most obvious threats available to a state.

But fines can be tricky to exact across borders, especially with bigger states, and if Australia says "change or we'll ban you later", the networks may play chicken and deal with it later, when the threat is real.

Starting with "you're banned" means it's painful now, and it's on the networks to prove they've changed and win a way back in, if they care. They might suddenly be willing to listen to how they need to change to get back in, and get that work done.

I'm not really in favour of bans on access to information or networks of people communicating, but a(n effective) ban does seem like a potentially effective tool to motivate action, even if it lacks nuance and doesn't solve the real problems.

I say "an effective" ban there because, come on, if it's just an age verifier then teenagers will figure it out and the whole thing is toothless, not ruthless.