You don’t need to be 18 to have a bank account, even in the UK (which just introduced age verification laws).
https://www.hsbc.co.uk/current-accounts/products/children/
https://www.barclays.co.uk/current-accounts/childrens-bank-a...
And there are banks and fintech companies which give you pre-paid cards which function as credit cards for online payments. You top them up whenever you want and that’s your spending limit. Parents can just hand those to kids for day-to-day operations.
In short, being able to pay 1$ online is not sufficient age verification.
> It just sucks
I agree. One mitigation around that could be the gifting of accounts. People lurk in more than one forum, so if you meet someone which seems to have their head in place and would be interested to join, you gift them the membership. Keep the association between accounts in a database for, say, one year to see how it goes. If someone repeatedly gifts accounts to people who end up being spammers, you revoke their gifting privileges.