Hunger for a specific bug, ability to live "wild", for sure...and then there's the whole "everything eats chicken" thing. which would require constant replenishing of the "bug eaters". That being said, agree that any chickens in a backyard flock that can pick off some lanternflies is a good thing.
The big problem with deer is that where they live and where we live is now the same in many places...kind of unsafe to hunt in a suburban neighborhood. Where it's safe, though, yeah, I'm with you on the rest!