Based on what? Have you spent any time in this state? Based on ~30 years of observation as a sports fan all over the state, I really don't think that is true.
Maybe you are trying to project your east-coast mentality, but it just doesn't hold up out here. Hockey has very little interest among the local population, and although we have a pretty significant # transplants I still don't see hockey even catching up even to soccer around here, and certainly not "dwarfing" it. I'd love for Seattle to have an NHL team, but I think there are some legit reasons why we don't have one. I used to sometimes go to see the Seattle Thunderbirds at KeyArena, and while it was always fun, the crowds were always tiny and sparse despite being in a prime, convenient location and having cheap tickets.
Beyond Seattle, I've lived in little rural towns in NW Washington and SW Washington, mid-sized cities as well, and you will always find a strong contingent of soccer fans even in the most backwater redneck towns, but nobody is really into hockey at all. In this state there are only 12 high schools that have hockey teams, and I think about half of them are smaller private schools in wealthy areas.
Look, I live much closer to Vancouver, BC than Seattle (about 1/3 the distance), and even though I'm hugging the border to the land that this obsessed with hockey I still see a very weak presence here. It's less than an hour drive to Vancouver, but I don't even know a single person who has ever been to a Canucks game. The bars around here have Sounders scarves hung up on the walls and the TVs are always set to soccer whenever it is on, but it is extremely rare to see someone watching hockey at the bar and I really don't think I've ever seen more than a couple stragglers watching a game. Among my current acquaintances I can count dozens and dozens of soccer fans, but I can only think of two hockey fans (and they are brothers who share a house). And I don't think it is a generational thing either, people in my dad's generation really don't give much of a shit about either sport.
Before the Sounders moved up to MLS and they weren't on every weekend, there were no scarves up on the walls, this is true, and Saturday afternoon were a toss-up for what was on TV at the sports bar, but every Saturday morning was still EPL and every mid-week Champions League match would draw small crowds. During the NHL playoffs you might see one or two people watching a hockey game on a silent TV in the corner.