Maybe, but you did admit you kill deer without camo. So, is it necessary?
I'm not saying camo doesn't work. Anything that breaks up your outline will help. I wear plaid wool, but I have to cover it with a big solid blaze orange vest and wear a hat too. Not exactly camo. It has never handicapped me from getting close. As long as you don't move when they're looking at you. You could be wearing a clown suit.
I'm not in a blind. I'm standing right out in the open sometimes, and can still fool them. They're looking for movement. It's not like they can't see you if you wear camo.
Camo was invented for the military to fool other humans. It works well for that.
Don't get scented, and don't move when they're looking at you. That will get you all the critters you want, and you don't need to try and look invisible.
As for the wafers. I really don't know if they work. It might be nice if there was an independent test to see if they do, or any of the other scent products.