Yes, their PSD2/SCA roll out was disastrous. The documentation is marginally better now, and to their credit they've also produced a lot of example code repositories showing end-to-end implementations of various scenarios in various programming languages. But then, the epic scale of a full API integration and the moderate scale of even a Checkout integration today, as shown in those docs and sample repos, only highlight how painful the whole process has become. Then you look at the modern services that are going back to what early Stripe did so well, handling most of the pain of charging customers for you with very straightforward integration requirements, and the differences are stark.