Oof that's bad. Makes it seem like ChatGPT is really more hacked together than we all want to admit.
ChatGPT is just a consumer of their identity/auth system though, same as their core product - the API. Considering ChatGPT came much later, it seems irrelevant.
I don't think their API is their core product. The chat application is not only used by more people, but it drives development of the API.
Drives more revenue too. But I still think in the long run, APIs will bring more revenue.