Poch doesn't use DM's. Even schneiderlin isn't an out and out DM.
If we used DM's, don't you think Dembele would have seen more game time?
Dembele is not a DM or at least he is not a specialist DM, he originally was an attacking midfielder for his former clubs.
Yeh I take your point about Schniederlin, I think when we talk about DM we refer to a very all round midfielder with excellent positional play, basically more than just a tackler.