So much specialized hardware and software has been designed to take advantage of the protocol. REST is really just an architectural guide for using HTTP as it was intended so that those tools can, ideally, provide some efficiency. The entity being transferred isn't really what matters. It's the metadata included about the entity, it's related resources, the client and server capabilities, the explicit expression of intent and result, and all the other header info that allows those tools to do their thing.

HTTPs ubiquity, for better or worse, makes it about the only option for any web based tool where control from end-to-end isn't a practical option. Better protocols can be made, better hardware and software can be made to utilize them, and some have, but their reach is very limited for now. Understanding the thing we're stuck with is pretty important. Luckily, countless man hours have gone into studying the protocol and building the tools that take advantage of it. Much of that information has been shared openly. I think that's a pretty big advantage over anything else.