"..today it would not be at all surprising to find that an engineering team has built a backend using REST even though the backend only talks to clients that the engineering team has full control over."

This bit is particularly important to me personally because I have been that guy in the past. As a new grad fresh out of college, someone taught me REST and I was.. impressed. I thought it was the only way to design web backends. It was my hammer and everything else I saw was a nail.

A few years on, I can look back and understand how stupid I was.