I have guys planting beans on beans for 25 years or more. And I have guys planting corn on corn for the same. Until a soil born pathogen of some type develops because of beans on beans, and cuts the yields down to nothing, farmers will continue to do it.
One thing about corn on corn is, you get slightly reduced yields when you first start out doing corn on corn. Then after about 4 years the yield seems to come right back. The problem is the cut worms, root worms and everything else stay around also.