Here's what I think it is, just saying.
Hockey is different than baseball in that regard, as every region of the US has a warm season, and kids grow up playing baseball most commonly. I think that's why baseball is always called America's game. You play it in gym, in the yard, doesn't take much to play.
Hockey used to be more of a cold winter Canada/US regional thing when it started (obviously you can build an ice rink anywhere, and a lot of areas have, but it's only been relatively recently that hockey has exploded in popularity). In Canada and areas of the US that make backyard ice hockey possible...it's huge there. It was just about exposure initially, I think.
The Original Six teams just represent the heart of hockey to a lot of fans more than historical early teams in baseball. They win, they have huge fanbases.
I'm sure that phenomena will fade as other teams get more money and success.
So the original six are like the Cubs, Red Sox, Yankees, Giants, Dodgers, and Cardinals then?