I care about REST because I remember SOAP and I am very happy that REST mostly won that war, at least in the public API space. I suppose there's something to his article about diverging from the idea of resource definitions but I hope that API providers stick to REST as closely as possible and don't do things such as require cookies in their API or have the app manage state some other non-RESTFUL way that isn't simply passing a token as a POST or GET value for example.