This is true. It is VERY true. I have experienced it in spades myself.
But....it comes with a downside. These communities can indeed see themselves as a more cohesive "us," and "we" who depend on each other....but the also look outward at anyone not in their "us" as a "them," and often not in a good way.
It's the flip side of living in a more diverse, urban community. You don't have contempt for "the other" as much because you deal with various flavors of "the other" in your daily life. Shit, the other day I picked up an order at Whataburger. The person who brough my food out was clearly born male, around 50, and dressed up with fabulous makeup, earrings, and his/her hair all did. He/she looked fabulous, and happy. Being a product of living in Austin for 30+ years, I just smiled to myself and thought "get down with your bad self." I know plenty of more rural types who would have thought and even said (although probably after they pulled away) "what the hell was that? Who did that queer think he was fooling?" or something along those lines. And, had he/she shown up in their town....not sure how friendly their greeting would have been.
We should all treat each other the way that many rural folks tend to treat each other in their small communities - pitch in together, lend a helping hand.
We should all have the tolerance and decency for "others" and "outsiders" the way that many urban folks feel for folks in their cities - live and let live, avoid hurtful judgmentalism.
Sure, there are outliers for both (plenty of mean assholes in the city who would have called WB person a queer, plenty of people in rural communities who aren't helpful at all when people need it), but there are general lessons to be learned. The common thread? Treat EVERYONE like "we." And don't just think of the "me."