I would then argue that REST and XML-RPC fit in different niches and solve different problems, even if there's some substantial overlap between them, so people

I would then argue that REST and XML-RPC fit in different niches and solve different problems, even if there's some substantial overlap between them, so people like the OP that argue that REST completely obviates the need for XML-RPC is missing the point. Human exploration of a loosely-defined API is great for certain use cases, but doesn't provide the hard API contract and level of tooling that is what lead to the adoption of SOAP in the first place. So people like the OP that whine that people don't get it, and insinuates that everyone who uses XML-RPC instead of SOAP is some sort of unenlightened idiot, aren't making a compelling case if they just ignore the whole reason why SOAP is popular.