What does stone ground mean? 

This is a milling method that crushes entire kernels between two stones. The result is fresh whole grain flour that is high in fatty acids, which turn rancid if stored for too long.

Why is stone ground flour not the norm?

Because steel rollers took over in the late 1870ies. This made it possible to remove bran and germ cleanly, to efficiently grind white flour for the masses. This process also increased the shelf-life of flour. 

Modern wheat and roller mills are a good match. Stone mills and heritage wheat are a good match. They do not mesh well. 

Is it necessary to revive and independent, local stone mills?

Yes! These mills are vital to supporting a regional grain economy. They are the bridge between (small-scale) farmers and bakers/ consumers. Their in-depth knowledge of the grain is essential to retain nutrients and flavor in the flour. 

Also, whole grain flour is best consumed fresh. So you really want a local mill close-by for the highest quality product.