Less teams = more competition, the titles mean just as much. Plus there were more than 6 teams, its just 6 teams lasted and are still around.
Except you're neglecting that the Leafs and Habs essentially had first dibs on most Canadian players, due to junior club affiliations, throughout the O6 era. Makes it significantly easier to stack the NHL clubs and fill the prospect cupboards when you've got easy access to the best prospects.
__________________ CanadianHockey________ __ __________Sens, Oilers, and Team Canada