[TOGoS]

> I even used HATEOAS principles when building HTTP APIs

I found your problem.

> About being able to use any API without understanding it first

That's a HATEOAS thing, as I understand it. REST just means that you have resources and verbs, and the verbs have ~relatively~ consistent meaning. If I see some GETs and PUTs and PATCHes and DELETEs I can get a pretty good idea of what's going on. It doesn't mean I understand all the details of your application logic.