Yeah, doing the math it's actually only 33 years of not supporting AF_UNIX, but that's not really right either, since those versions of Windows didn't support any sockets. I guess the technically correct answer then is that Windows didn't support UDS for 26 years.

Which is still enough for most portable software to go "eh, localhost is fine*"

* resolving localhost is actually a pretty bad idea (yet very common) and it's way more robust to listen directly on a numeric address.