The Amish are one of the few healthy communities in the modern world by the simplest and most profound metric.
At the same time, they aren’t able to excel in math, technology, art, or society. Their (very effective and admirable) solution is also self-limiting.
But the Mormon model isn’t ideal either. It allows more individual and family excellence and much more missionary work. But it isn’t as good at promoting real community (I know, because I grew up in an old-fashioned stake in one of the Mormon settlements on the Deseret periphery that was still run the old way, and I can see the very big distance between then and now. It’s not just my youthful nostalgia either. My father moved there as an adult from the urban wards where he grew up; he gets choked up remembering the experience). And it isn’t as effective at retaining the young or even at having young. Though still quite good, mind you.
What’s needed, I think, is for Mormons to capture a little bit of that old experimental flair. We need more Mormon intentional communities. All kinds of efforts. We need more failures, basically.