This is of course true, and has been for awhile. As far back as the 70's, 80's even topflight Canadian NHL talent was barely winning. Even in Canada Cups Russia, Sweden, Finland, could hang with us and then Later the US as well. This resulted in pretty much of a panic in Canada to revamp our game, tweak it, make it better, make systems better, match training of athletes, basically did a lot deeper. This to me resulted in Canada getting ahead again but I do feel that the next time we are caught, and I believe it is happening already in Junior Hockey, Canada won't be able to separate anymore.
Finally, the fall of the Iron Curtain has certainly diminished Russian opposition. This has been good news for Canada for decades. We might not have had as much success against a trained Red Army Machine practicing together all the time and going to the Olympics. Russian players and teams are at a severe disadvantage of course (as are most other hockey nations except Canada/US) because a large proportion of their star players are playing here, or elsewhere.
In NA we don't have as much of that problem. This is the NHL benefit to Canada, and the US, IF they actually went to the Olympics.