It was all regional scouting rights.
And all the players in those days came mostly from Ontario and Quebec provinces and they inherently belonged to Toronto and Montreal.
And also… no players from Europe. No Russians. And very few American players.
The U.S. teams got screwed in a rigged system in a 6 team league.
It just wasn’t fair.
Rangers, Red Wings, Bruins, and Blackhawks had to settle for other parts of Canada to find players and hopefully get some luck.
It all started to change in the late-60’s and early-70’s with expansion, the advent of the NHL Draft, and the end of regional rights scouting.
I don’t want to devalue the accomplishments of what those teams in Montreal or Toronto did in those days….
But they had maybe the most grossly favorable circumstances in which to build teams and the league did nothing about it for 40 years. So those teams built dynasties with absolutely nothing to stop them and no obstacles in their path.