Must be an old story, but I just read it, what’s your opinion on corn and the likes in dog food?

http://www.dogbreedinfo.com/care/corndogfood.htm

'A dog's body cannot process corn properly. It is difficult for them to digest it. Corn is a cheap filler, a starchy energy which serves little to no nutritional value. A lot of it comes out in their waste.'

This makes sense to me?