>misusing it just decreases clarity and hinders communication

There is no such thing as "misusing language". Language changes. It always does.

Maybe you grew up in an area of the world where it's really consistent everywhere, but in my experience I'm going to have a harder time understanding people even two to three villages away.

Because language always changes.

Words mean a particular thing at a point in time and space. At another one, they might mean something completely different. And that's fine.

You can like it or dislike it, that's up to you. However, I'd say every little bit of negative thoughts in that area only serve to make yourself miserable, since humanity and language at large just aren't consistent.

And that's ok. Be it REST, literally or even a normal word such as 'nice', which used to mean something like 'foolish'.

Again, language is inconsistent by default and meanings never stay the same for long - the more a terminus technicus gets adapted by the wider population, the more its meaning gets widened and/or changed.

One solution for this is to just say "REST in its original meaning" when referring to what is now the exception instead of the norm.