Is the Norris the award for being the tallest dwarf or the best Dman in the league?
I'd say that having the strongest positive influence on your team's performance out of all defensemen in NHL is a pretty good starting point for what it's about. Then there's the other stuff such as the strongest offensive season in 30 years.
He had over 50% more 5v5 points than the second-best offensive 5v5 defenseman in NHL. Of course, you might not understand just how great of an achievement that is, so take a look at when it was last accomplished.
The last time it was close, was a 47% gap in 11-12. Also by Erik Karlsson, by the way. 48.4% was by Leetch in 96-97.
The last time the feat was accomplished was in 1985-1986 when Paul Coffey had 90 ES points, and #2 had 49. Paul Coffey scored 138 points that season, and of course, was playing with a 215-point prime Wayne Gretzky.
Karlsson's teammates on the Sharks... let's say they're not on the level of prime Gretzky.
Of course, if we want to look for when this was accomplished without the help of Gretzky, we need to go all the way back to Bobby Orr.