The intent is simple, but there are many ways to express that intent. Some of them work well when there are two components sitting right next to each other in m

The intent is simple, but there are many ways to express that intent. Some of them work well when there are two components sitting right next to each other in memory on one machine; others work well for an unknown number of components interacting with each other over a slow, unreliable network. Even if RPC is a fundamentally, unambiguously simpler way to express that intent (and I think that's arguable), it does not meet the same technical requirements that REST does.