It would help avoid these issues, but if you're a payments startup then you probably want to actually keep some control over your core business instead of just

It would help avoid these issues, but if you're a payments startup then you probably want to actually keep some control over your core business instead of just being a reseller intermediary for an actual payments company which holds your customer's money, has all the leverage over what features and policies "your" product will have and gets most of the profit.