First, I’m going to snip down some of this so that everyone isn’t just tl:dr as I refute like 5 points.
Because the Stanley Cup is a league trophy (yes I know it’s technically a “challenge cup” available to all, but it’s a league trophy). You aren’t arguing that the KHL or SHL or Liiga should award their championships every 4 years are you? What makes these international competitions special is they don’t happen every year.
While the World Championship and the NHL have been around for about the same length (NHL 1917, WC 1920) the WC did not begin allowing professional players until 1976, so in terms of best-on-best the WC is about 60 years behind.
First off, the Stanley Cup Playoffs typically end around the third week in June, and the players are all over it. That’s because it’s currently the closest to best-on-best we have.
Second, the football season in Europe is over by the end of may. There’s two teams (out of like 100) playing for the CL trophy, and everyone else is done. The WC/Euros is still a week after the CL final, which is exactly what I’m suggesting: a best-on-best tournament in late June.
Oh they absolutely did object to that, but the World Cup is an institution, while the WC is not. The (football) players care about the World Cup. The (hockey) players don’t care about the WC. The solution is to make it more accessible.