Find all the anecdotal evidence you wish to dig up, I can tell you through personal experience and with 100% honesty that I have seen precisely two mosquitoes all summer long. Think about that in the context of just how much time I spend recreating in the outdoors. And neither one was particularly interested in me.
What you've found online can be explained by the fact that both Utah County and Salt Lake County include extensive marshlands and wetlands along Utah Lake and the Great Salt Lake, respectively, that create an environment that does not extend anywhere beyond those shorelines. There are even pelicans out there in that part of landlocked Utah. No one lives anywhere even remotely close to the Great Salt Lake, so any mosquito issues that may exist out there are non-issues for the human population other than duck hunters.
You may well have a point about the shorter life cycle in the high alpine areas. That may be the subject of research, and the Northern Rockies are a remarkably different climate then anywhere within Utah's borders. But I find it hard to imagine that anywhere could possibly be worse than the wilderness canoe waters of northern Minnesota and Ontario. At least when I lived in Florida they sprayed for mosquitoes there. Florida, though, is a true Jurassic Park for every other kind of creature imaginable, insect and otherwise, so I'm not really sure that I should throw that out there as a shining example .

The key to breeding mosquitoes is standing water, but my comments regarding bugs in Utah are not limited to mosquitoes. There's really not much here at all besides ants, a single week of biting black flies in the Uintas and the occasional spider or beetle, for any insect requires reliable water to breed and survive. There's certainly nothing here that would annoy you persistently. The Northeast is insect hell by comparison. Scratch that... There really is no comparison.