The UX in UI/UX is kind of silly?

This post is a spontaneous rant.

I have used the term "UI/UX" times in recent years but I suddenly feel that it's kind of silly: is there even a real boundary between UI and UX?

Every good, experienced designer, past and present, would tell you that both aesthetics and functionality are important.

So how did UI suddenly come to mean just the button of a kettle? Or just the handle? Or just the lid?

Hasn't the interface always been the part that abstracts away all the complexities users don't need to know in order to operate the kettle effectively? And, therefore, hasn't good UX always been a fundamental part of good UI?