DCOM "failed" because (a) it's based on COM which is based on C++ style vtables and is hard to version/consume, and (b) because doing reference counting over the internet is never going to work well.

But I work in the industrial automation space and we deal with OPC-DA all the time, which is layered on top of DCOM which is layered on COM on Windows. DCOM is a pain to administer, and the "hardening" patch a couple of years ago only made it worse. These things linger.

SOAP was nice and simple until the Architecture Astronauts got their hands on it and layered-on lots of higher level services.

MCP isn't really like either of these - its an application-level protocol, not a general-purpose one.