PostREST is a hack, a bad one. Every time I'm seing that tech coming up, I'm like why would anyone use something like that, so much limitation and coupling.
PostgREST is a phenomenal project, and you get A LOT for it's design. How many thousands of applications are simply wrappers around CRUD databases? PostgREST gives a great REST API implementation for exactly this use case. PostgREST probably has a more robust API interface than 70% of basic CRUD apps, with RLS built in.
Am I using PostgREST for a project with lots of complex backend logic, long running tasks, etc? Absolutely not. But that's not what it was built for.
Coupling isn't intrinsically bad. You could design a three tier architecture with all sorts of loose coupling, or with PostgREST you could have a one or two tier architecture with orders of magnitude less code but tight coupling. I'm not sure why the first choice is necessarily better in all cases.
