Because Seattle straddles state freeways at their busiest points, it should be ready to absorb the traffic when they’re disrupted.
What this means in practice, of course, is neighorhoods need to be razed to accommodate the suburbanites who wish to drive through them. There is no other way to "aborb the traffic" of a freeway, which carry 1800 cars per lane per hour at capacity. That's the point, and flaw, of freeways. They carry quite a few cars (though not with the capacity people think they have), but they have to dump them off into lower capacity roads eventually. Sometimes even in places where people live!
When suburbanites complain about lack of parking in Philadelphia (a related, but not identical issue, of people thinking that where I live needs to accommodate their wants for some reason), I joke that I would like to lead a convoy of 2000 cars from Philadelphia and go park them (legally!) in some random neighborhood in the suburbs and then just go wander around. People would flip their shit. The response to this is always something like, "what do you expect, you live in the city." Yes, yes, I do, but that doesn't mean I have to turn my neighborhood into a parking lot just for you.