Actual REST may well not be the right solution for quite a lot of the problems people have with APIs, so its good that people should not always feel obligated to use REST.
OTOH, actual REST may well be the solution for other problems, and its a lot easier to talk about solutions if we use "REST" to refer to Representational State Transfer as defined by Fielding and let all things that aren't that get names that reflect what they are, whether its JSON-RPC-over-HTTP or something else.
Its a lot harder to talk about the merits of different approaches if a wide swath of unrelated approaches that are not similar except in not being SOAP+WSDL (or, possibly, in that plus also not being Fielding's Representational State Transfer) all get lumped together as "REST".