Palace often play without a striker, so Zaha (particularly) and Townsend have freedom to roam where the space is. While he operates from the left side, he is far from a chalk on the boots type and has developed a game that works well centrally and even over on the right.
Also, crossing is not the point of dribbling. It would be like levelling the same issue at Dembele. The point of dribbling is to create space, something Zaha excels at and we struggle to do against defensively set teams. If Zaha can pull two defenders out of place and lay it off, for example, we are laughing considering its Alli/Eriksen/Kane getting the ball, in those areas, with space.
You need to refine your understanding of the player, because whenever you talk about him you appear to be talking about someone else entirely.
Ive always seen NKoudou as a right sided player, not sure why then Schlupp would have anything to do with him. Though, as I said, it was speculative anyway. I actually like NKoudou, I think theres somehting about him - but it seems clear he wont be getting chances here.