It’s not a question of tech, and more a question of “worldliness” that breaks a community apart. As tech advanced back in the day they saw communities drift apart and didn’t want that to happen to them. It just so happened that these types of spiritual movements and awakenings were a big thing back in those times.

Also it depends on the community of Amish as well. Many of them use their own off the grid power, and even use computers and power tools for their businesses and shops. In that sense it’s more about self reliance at that point