There's no such thing as hair being prevented from growing by "Debris on the scalp", look at ingrowing hairs, they don't stop growing even when they are turned inwards, hair loss is caused by your hair stopping growing, and falling out more often.
The significance of washing your hair is to remove sebum, not because it blocks anything but because it contains high levels of DHT, which is involved in making your hair fall out, so remove the sebum, remove the DHT, reduce the problem.
Nioxin apparently works well, but I use Nanogen's Anti-DHT shampoo as I can get it cheaper. It doesn't make your hair grow again, but it definitely reduces the amount falling out, which I'm content with. Can't post a link but search for Nanogen and I'm sure you'll find it