[jjeaff]

I see no reason why one wouldn't self host this. Subscription and billing data is such a crucial part of any business, I'm surprised more don't handle it internally.

[Palmik]

Because to self host it, you'd need to ensure you're PCI compliant. That works for established companies I guess, but not so much when starting out.

Payment provider lock-in in a scary thing, when they can cancel your account at moment's notice.