[_heimdall]

I haven't seen a REST API in production for many years, maybe 15?

That's anecdotal obviously, but almost every, if not every, API I use today is an RPC call returning JSON.

Edit: to be clear, the distinction between what REST was defined as and what we use today often doesn't really matter. We use JSON APIs today, it is what it is. This is a case where it really matters though, LLM companies are now trying to push an entirely new protocol that tries to do roughly what REST did in the first place.