I love this note on the fly.io site about requiring credit cards:

Even for our free services, we require a credit card number. We know that's the worst and it gives you heartburn. It's not because we plan to charge you.

But here's what happens if you give people freemium full access to a hosting platform: lots and lots of free VMs mining for cryptocurrencies.

We could tell you we want to prevent crypto mining because we care about the planet, and that would be true. We also have a capitalism nerve that hurts when people spend our money gambling. Your credit card number is the thin plastic line between us and chaos.