Bill de hÓra on HTTP methods:
I’d encourage anyone not to make the assumption that POST is the prime method and hence the most powerful, when in fact it’s merely the least meaningful (and likely hiding a design flaw around resource naming) . It’s what you use when the others don’t fit the problem. It’s not like we encourage programmers to call all their methods “execute”.
+1. Of course using GET and POST is better than using GET or POST only (I have a hard time figuring out whether the POX-style all-GET or the WS-style all-POST way is worse, BTW), but of course relying on more shared semantics and the idempotency guarantees of PUT and DELETE is even better. I would claim that having a few more (ideally idempotent) verbs would be even better (although the cost of introducing them is probably prohibitive).
all-POST is better than having even one non-safe operation implemented as GET.