Not sure if they still do this, but when I first started learning, front and center of the documentation was telling you how to do it in a mobile app, then JS SPA app. The use case of a backend API+JS/mobile frontend was buried. And it was all stupidly named. It wasn't blatant like 1) MOBILE APP FRONTEND 2) JS APP FRONTEND 3) API BACKEND + FRONTEND.

So for me, mobile wasn't relevant, SPA wasn't relevant, and my use case, the third one was hard to find.