[lmm]

> Strict, automatically-checked schemata for APIs are perfectly doable with REST, JSON or whatever Protobuf flavor.

Up to a point, but having a single standard that's built into all the tooling is huge. Hopefully one or other approach will "win" in the REST world and we'll start to see some convergence.

> As for the easy-in-the-browser part (whether it is for tests or implementation), it was merely a side effect of reusing the HTTP spec semantics as a common-ground general purpose vocabulary.

Intended or otherwise, it was a big advantage, and I think it was the real reason for "REST"'s success.