I think the "wheat domesticated humans" argument is about changes to our behavior, our culture and social structures, rather than genetic change. It isn't domestication in the evolutionary sense. It would be like keeping zebras on a farm with horses and doing your best to tame and train them. You might be able to change their behavior so that they behaved differently from wild zebras, but it wouldn't be domestication unless you bred them over generations to produce a population that was genetically different from wild zebras.