I've already linked in another comment on this thread so I won't repeat it, but there's a book explaining why. I didn't know this prior to reading the book, but the original intent of RESTful APIs were to use hypermedia as the engine of application state (HATEOAS). Terrible acronym, but a really interesting idea.
There's a lot to say about it, but the essential idea is that if you let the server control the state of the application via hypermedia requests/responses, you eliminate a lot of the complexity that is associated with client-side web apps.
There's a lot to say about it, but the essential idea is that if you let the server control the state of the application via hypermedia requests/responses, you eliminate a lot of the complexity that is associated with client-side web apps.