My biggest hesitation with these things is that there is no limit to the possible bill I may receive when the agent goes haywire. Cloudflare doesn’t see this as a problem of course.

There's a whole payment section in the submitted article which addresses your concern, perhaps you should read it.

It's not Cloudflare's job to see what you choose to buy as a problem.

I'd assume they want to limit the number of bills that will get disputed.