I guess my point is that payment and ledger back-ends aren't the hardest part about running a bank, they aren't even the hardest technology component. This isn't "for developers" in the same sense that Stripe is. It is for people ready to run a bank. Sure it will save you paying lawyers and regulators for charters and it will save you from buying a mainframe to run some crufty COBOL ledger but that still leaves a lot of yak shaving before you even get to the interesting part of your Fintech product.

Okta is successful because almost every application needs authentication, almost every organization needs SSO, and no one considers it a core competency.

The intersection of organizations who can run a bank but don't already have entrenched software to do so, and want to build all the other software themselves seems vanishingly small.