There's ~1.5 billion credit cards out there. By definition, every startup is going to ignore pretty large segments of the addressable market (e.g. people who only speak languages not familiar to the starting team). Starting with an addressable market of 1.5 billion is not a bad thing.

Payments are complex and can be extremely localized. This is IMHO not a battle for an early-stage startup to fight. Credit cards are as close as there is to a de facto international standard; go with those to start.

Also -- in my experience, people without CCs reach out and ask for alternate arrangements if they want your service. This is an appropriate time to make sure that e.g. companies that require a complex PO process are spending enough to make it worth your time.