This is an excellent point, standards are always a good thing and ideally every service should be built in compliance with them. Sometimes, however, it makes business sense to break the "rules" (for example I recently built a supposedly RESTful API for a client which wasn't able to issue a DELETE request). My advice is therefore that any service which meets any of the points in my post should be described simply as "an HTTP web service" and avoid all the labelling and resultant flame wars of REST.