I would disagree that Trip-hop is more broad. Trip-hop seems much more specific.
As far as Endtroducing being the first instrumental hip hop album, I guess one could argue that. However, it's a bit like saying that Iggy Pop and the Stooges were the first punk band. Either way, even though both movements come from an earlier time it didn't get much attention until the following decade. It would be akin to arguing that grunge isn't a genre from the 90s because Dinosaur Jr. was around in 87.
As far as Endtroducing being the first instrumental hip hop album, I guess one could argue that. However, it's a bit like saying that Iggy Pop and the Stooges were the first punk band. Either way, even though both movements come from an earlier time it didn't get much attention until the following decade. It would be akin to arguing that grunge isn't a genre from the 90s because Dinosaur Jr. was around in 87.