I’ve heard the same type of argument a long time ago against choosing wordpress when it was still relatively new (usually from custom webdev shops when talking to clients)
Even with WordPress the assumption that you pay for it in the future is valid. Albeit anecdotal, I have always needed to rewrite from scratch after first launching on WordPress. But that doesn't have to be a bad thing. Often with tools that help you bootstrap quickly, say ORM's, GraphQL, and in this case PostgREST there comes a time that optimizing or extending is more work than writing a custom build solution. You have to decide if time to market or validating your business model is more important than a potential premature optimization.
There are definitely the right tools for the right job. I work in enterprise on applications that will run for decades. It makes no sense for us to sacrifice long term maintainability to ship something fast.
