I have been the service provider who had to paywall just to stop the spammers and you're right. But it's also true that kids will be collateral damage (or anyone without a credit card).

In my case, and it was the 90s, I took the time to setup a way to pay by calling a premium (1-900) for $1.49 number so the barrier to entry even for kids was still reasonable.

Maybe in modern day the equivalent is adding Google pay and Apple pay then you cover some kids at least (gift cards and such).

Quite the hassle for the provider, and it will turn away any person who cares about privacy. There's no way to win anymore.