I know i'm a "newb" but I know that deer actually make the roar (or growl or beller whatever you wanna call it). I heard it last season right before peak rut when the bucks where still in chase mode. A decent 7-pointer was running a doe hard and growled extremely loud and my jaw dropped, never heard of or witnessed anything like it, but i definatly believe they do it.
I guess my point is, just because you've never heard it doesn't mean it doesn't happen.