Ah yeah, there was a discussion I listened to somewhere on that, the gist was that Linked Data is primarily semantic, whereas ATProtocol lexicons are primary schematic. So the whole schematic/semantic debate. I imagine Linked Data can have all sorts of schematic aspects too, but that would be the shoe-horning route, and it sounded pretty convincing to me that such specs should be primarily schematic. This wasn't the longer discussion (can't find that) but this bit in this video touches on the general debate.