While the statement implying that modern farmers are good Shepard's of soil quality is... debatable at best and I'd argue mostly false it is certainly true that, as a rule, deeper / larger root structures benefit soil rather than diminishing. Especially within the same family of crops deeper roots will always result in a healthier soil than shallow.
I don't remember saying they are good shepherds. Just keenly aware. The usual solution is to dump many tons of petrochemical based fertilizers and amendments into their soil which washes off into local waterways.
