There are different lenses on which to talk about semantic technologies. I don't happen to share the one that says they must use URIs and all that semantic web stuff. That's simply one way to do it, and not the only way. On the ONTOLOG list, there are occasional comments that URIs are not necessarily the "best" way to do. Wikipedia says this:In software, semantic technology encodes meanings separately from data and content files, and separately from application code.This enables machines as well as people to understand, share and reason with them at execution time. With semantic technologies, adding, changing and implementing new relationships or interconnecting programs in a different way can be just as simple as changing the external model that these programs share.
From that, we can infer that any frame-like representation, mostly growing from Charles Fillmore's Case Frames by way of Marvin Minsky's work on frame languages, is a semantic technology. The much more recent proliferation of URIs grew out of a need to solve an interesting problem, turning the web into a kind of knowledge base.
I am not taking any side on whether URIs are necessary; I believe they have their place.