A lot of this is not about increased yield, but healthier more nutritious plants, a healthier soil that binds more carbon, a more diverse farmland supporting a more diverse set of insects and animals and so forth.

The monocropped modern agriculture is not only producing dead soil, farmers that become reliant upon exterior input supplied by global conglomerates (i.e. ther margins don't go to the person doing the farming, but everyone suppling the stuff the farmer needs), and causes a lot of damage to local ecosystems.