I wonder if a healthy tech economy isn't more of an emergent behavior, and it tends to emerge in cities because there are more people, more resources, and more opportunities all mixing together.
You need good communications infrastructure, not just fiber but cellular too. If all you have available is satellite or (gulp) DSL, it's really painful to get work done. But that requires an enormous financial investment, especially in rural areas where RoI-per-mile is mostly negative.
Often the rural areas already have a culture there, and that culture doesn't necessarily want to get along with tech. Here, cellular providers can't deploy new towers because too many people are convinced that they'll get cancer, including some members of city council. Rural areas will tend to be mostly populated by people who either moved to get away from the city, or have never experienced life in a city. For those people, there's very little about a strong tech scene that sounds marketably attractive.
That also means that the talent just isn't there. And talent isn't there in part because opportunity isn't there. And opportunity isn't there because talent and infrastructure aren't there.
Nobody wants to just pump half a billion dollars or more into a small town just to see what shakes out, and if you did, you'd probably only end up ruining everything that made it an attractive enough small town to experiment with in the first place.
This is all really a shame, because it's contributing to a lot of the political and economic divide in this country, as rural areas are neglected, and shrink, and die slow deaths, while people all jostle for tiny amounts of space at high cost in dense population centers.