With REST we cannot truly define a degree of understanding. Such a definition would assume that multiple people know and agree on what would be the full extent

With REST we cannot truly define a degree of understanding. Such a definition would assume that multiple people know and agree on what would be the full extent of that understanding. The problem with REST is not the different amount of knowledge that people possess, but the different ideas that they have about REST. Which is another way to say that REST is not really a well defined protocol. (Have you seen similar vague posts titled "What IMAP4 actually means"?) Because it is not a well defined protocol, you cannot use the same client library to access random REST APIs. You use/write one library to access Twitter's REST and another to access Facebook's REST. You could argue that you use HTTP in both cases, but that's just the underlying transport protocol - not the API "language" itself. Because of that fact I blame REST for the millions of developers hours wasted in re-implementations of hundreds and thousands versions of the same "concept". The REST "idea" sure looks sexy when you put it next to an atrocity like SOAP, but that's one of its very few merits.