I think I've made this point before, Mik, but I think you're viewing this issue from a strictly scene based perspective.
There are another lot of DJs who play vinyl because they always have done, have collections with old original records across all sorts of genres, some of which they bought as new, some they've collected from second hand vinyl shops, boot sales, charity shops etc. These people also buy new vinyl regularly. Most of them are aware of the scenes like the NS scene but aren't actively a part of it.
So when the likes of Juno advertise each week's new releases, they're as likely to buy a couple of Outta Site releases as they are new House or D&B releases, dub 12s, Nu disco or the latest Bamboos single. They play sets that cross all genres without subscribing to any particular scene. The reason they'll buy a repress is because they hear it and like it - they may be unaware that there's an expensive original or it may just be of no interest to them that there is one. One thing I'm sure of is that they are not pretending to to be some top Northern, mod or R&b jock - they don't play at those venues or to that audience.
I guess there's likely to be a temptation from the good folks on this site to look down on these DJs, but that's kind of missing the point: to expect someone who isn't part of a particular scene to nevertheless conform with its values isn't logical. That way we'd trying cats for murder every time they kill a bird.