I'm not claiming that XML-RPC or SOAP is "crappy"; there might be poorly-designed implementations (and of REST also!), but both have vital and important use cas

I'm not claiming that XML-RPC or SOAP is "crappy"; there might be poorly-designed implementations (and of REST also!), but both have vital and important use cases. I have never used SOAP, but have both designed and consumed many XML-RPC APIs, and have no problem with them. It's very important to use accurate terminology when discussing software and technology. The statement "Foo.com uses a REST API" only contains useful information if 'REST' is meaningfully defined. If 'REST' is redefined as a synonym for 'XML-RPC', then we lose the ability to distinguish between a REST and XML-RPC API in written or spoken conversation. I am not making any value judgment regarding either API style; they are simply different, and should be kept distinct for the purposes of communication.