Diamond formation Counter

So I’m watching a six man football game replay and I notice that the diamond formation that six man offense run is like a cheat code. So I was thinking as a former eight man football player, why doesn’t a DC counter a diamond by using 4-0-2 formation? Have four down line man send them all and trust your corners to cover them. But if they make a completion in the middle which they probably won’t. Because they only have two receivers theirs no point to have a linebacker not rushing. Just saying.