You may disagree based on observations of generally poor habitat in disturbed lowland streams. Given the proper tools, these streams will repair themselves to a remarkable degree - usually inspite of improper habitat recovery techniques. I reviewed a few web sites regarding Wisconsin trout stream rehabilitation. A better understanding of hydrology and riparian management would have prevented the poor investment in these techniques. The higher gradient streams in PA will actually benefit from simple structure, but probably not from structure built without regard to the hydrograph of the stream.
Many techniques work in the proper hands.
People need to practice before they get it right.