The publishers who make a lot of their money on it?
While YOU may not care about consoles, most big publishers do care about consoles a lot more than about the PC, as is obvious every time someone from EA or Activision opens their mouth.
And like it or not, those publishers are the same ones who produce most of the big games on the PC, and Gamestop does have some power over them.
Trying to leverage their place as a large retailer of console games to force publishers to make concessions for selling games in Impulse (even assuming they have enough clout to pull this off) is setting themselves up for a major lawsuit for anti-competitive practices. Gamestop already isn't particularly popular with many publishers due to used sales, and I'm sure several of the large publishers wouldn't mind the chance to take Gamestop down a notch if they started engaging in clear anti-competitive practices.
I actually agree with you.
I just think that they might try it anyway (wouldn't be the first time) on a more limited scale than forcing publishers to give them exclusives.
I have no personal experience with Gamestop so I don't know what they might do, and I'm indifferent toward them.
Trying to leverage their retail power to favour Impulse just sounds like a potential strategy they might go for.