The other thing is cutting your teeth and rising up in corps isn’t as bad as the banking / law track. Really don’t see why you would go the services track. Won’t encourage my children to go that way if they want to make a career doing private sector business things.
A very large, say property developer, might hire GS for its fundraising needs, but a GS grad wouldn't want to work laying bricks. He might want to work as CFO or someone very close to the CFO, but those roles are much harder to get than working as grad for GS.
So it's not just about what the grad wants, it's also about what he can get.
This shouldn't be controversial. Anyone who's been in the industry knows that people move "up" from IB to their clients. Of course everyone wants that, but again such roles are harder to get than IB.
However if you start at GS/another IB then you get plugged into a network where you see a lot more of these opportunities without having to go out to look for them as much. It's partially a numbers game so the more opportunities you see the better the chance of landing one.