I should mention my wife is currently 292 out of >30,000 entrants…and she selected her team based on a few riders she recognized when she half listens to me talk about the Tour…or if somebody had a cool sounding name (e.g. Jai Hindley).
As a sprinter, you’re almost always guaranteed to finish in the top 20. Even if you don’t win, you’re one of the first to finish during a sprint stage. Not the case for GC riders. A GC contender might win 1 or 2 stages and often finish outside the top 20 (even in hilly/mountain stages).
Of course, there are points available for GC position as well. So there is a balance to be found. But it makes sense to fill all your open spots with sprinters?