It's the same as how everyone has a culture, but a fair number of members of the dominant culture of an area only think of culture as something other people have - them, they're just "normal". Most Anthropology 101 classes have to spend a week or so smacking this idea into a few of the privileged who've made it to college without having their noses rubbed in the idea that not everyone out there shares their ideas, mores and opinions (nor *gasp* do they want to) - then everyone can get on with the class material.
In linguistics class, it always struck me as academic snobbery that threw the western-most third of the country into one dialect, especially after seeing My Fair Lady where (and I can't find the quote after a half-hour of Googling, so you will have to bear with me) Professor Henry Higgins says something on the order of how you can place the suburb a Londoner grew up in by accent, if not the exact street. London such a hotbed of accents, New Guinea such a plethora of different and unrelated languages, and the entirety of ten states speaks all one dialect, right. This beside the empirical fact that my mother's Idaho-native speech differed from my father's Utah-native version in easily detectable ways. Good grief, what about California? if nothing else. Difficult to so successfully satirize something like 'valley-girl' speak if it doesn't really exist, for only one example.
But you know, if you're happy with and invested in the idea that you as a PNW-er don't have an accent, you're not going to take kindly to someone telling you otherwise, complete with odd descriptors like "creaky voice" for some of its quirks. I'd call it more of a burr than a creak, but I knew exactly what was being talked about when I read about it.
Then again, I've been accused of being a closet Canadian for some of my speech patterns. To which I say, pity they won't take that as evidence at the border.