I guess it comes down to whether you feel there is a big difference between a "capable" 3rd liner and an exceptional one.
I see guys like Ortmeyer, Moore, Hollweg, et al. as capable 3rd line players. These guys could score plenty in the AHL but can't translate the offensive side to the NHL, so instead they maintain a roster spot through hard work and hustle; promote them to a top line for a few games to cover an injury and they look ineffectual.
Exceptional third line players on the other hand can finish given the chance, but are just better suited to the defensive roll. They're more comfortable playing a shutdown roll, but still manage to chip in 20 odd goals on a good year. Holik is a good example of this type of player IMO, (remember when Sather had him as a top 2 center?).
Now, I'm not comparing Korpikoski's game to Holik's. I'm simply suggesting that developing into a top bottom six winger is not the same thing as playing there because you couldn't put it together as a primary scorer...