Don't forget Goodman Games built a great reputation in 3e and I have tio believe that has carried over to 4e for their fans. Without that
I imagine it would be a lot tougher for someone new to the scene to have that type of success.
Which leaves him as the de facto 3pp for 4e. Moreover his major competition for customer share is Paizo, not Wotc because Paizo is holding a share from his potential market.