I don’t think there are too many Amish on the interwebs to answer your question.
They do speak to non-Amish people who visit their communities.
Fictional books about the travails of Amish life fill the shelves of Christian bookstores making things falsely idyllic, and Mennonites speak with Amish people from time to time. Mennonites would use the web. And there are non-Amish people who do join them from time to time.
Would you want anyone to be brought into or kept under this bondage to human rules? Perhaps in time, the fallacies they live by can be communicated to them - over time - can make a difference.
Why live a life of mega-legalism?
There are several Amish settlements in my area and one of them does have internet in their school.
There are a few, but they don’t do anything that is modern out in the open.