More importantly to her, it is a year-round habitat, a place where animals and plants interact. If I went there and cut all that stuff down, there wouldn't be any food there. There wouldn't be cover. In fact, critters love the dead leaves and brush, the old seed heads that provide both nourishment and shelter going into the harshest months of the year. Song sparrows and goldfinches that visit her yard dive after the aging purple coneflowers, the prairie grasses going brown and dry.
Birds peck out seeds to eat, scattering more to germinate into new plants.
Stalks and old flower heads and the leaves that find their way into his perennial beds are going to stay put all winter. It's nature's way of mulching naturally. Then he will shred the old material and put it back on the beds as mulch. The most modest condo garden can shelter birds or squirrels when icy winds make the landscape bleak and unwelcoming. So if you like the look of foliage and the idea of creating a habitat for wildlife, there's no reason you must chop and rake and clean out in the fall, even though that has been the traditional advice.