In my experience, the people with the horror stories and most extreme opinions are the people with the least experience. (Same thing with race.)
You’re right, Seattle is much more livable for families. My perspective is from SF, and it adopts similar policies as Seattle (which is why I unfairly lumped the two together) but SF has implemented them with much worse effect. I think it’s partly because SF is more compressed and usually lacks clear boundaries between neighborhoods that are good for families and those that aren’t, with a couple exceptions (e.g. Noe Valley).