Because in Soccer the clubs came first, then the leagues which are pyramids. The clubs are teams that have built up and been able to stay in the top division. It is not a franchise model. If a club is able to build up their club and maintain the finances, they are able to be in the top divison, if not, they are replaced by a different team. NHL operates off franchise values, the league is owned by the 32 franchises and grants franchise their right to exist (i.e., the other 31 teams grant a new franchise which becomes a co-owner of the league)
Many clubs in top divisions of their respective countries would be valued at much smaller than the average NHL franchise even though the sport is much more popular in their countries and bigger globally.
This.
It's entirely the difference between OPEN and CLOSED leagues. I'm from Rochester, NY. I learned very early that my teams were minor league, and were always going to be minor league, and no amount of success would matter.
So I picked an NHL and MLB team that played in the closed major leagues; I got Islanders and Mets on SportsChannel and those are my teams, even though I'm seven hours from their home venues.
In Europe, my devotion to my hometown club affects their chances of success. The club uses the money I give them to try and win promotion. My devotion to, and spending on the Rochester Red Wings wouldn't keep Cal Ripken from being promoted to the Baltimore Orioles. But in Europe it can.
Rochester was really into soccer when we got a team, because we thought that our devotion COULD get us a Major League team in that sport. And then once MLB bypassed us for TV markets like the other closed leagues, support fell to pieces.
There's no reason to be a die-hard, devoted, high spending fan of a minor league city when there's no upward mobility. When you're in an open system, there's every reason to support your town.