they wouldn't be that bad but devve is a key player in Astralis. Literally most of the strats are based on him to trade, make a play, etc. He is the star player of Astralis(even when it doesn't seem like he is).
Yeah, and the team takes pains to put him into those positions. Dupreeh and Xyp9x don't have that luxury yet still make crucial plays. Take one of those players out and the team would take a much bigger hit, especially dupreeh.