Wheat has a lot of fructans, which ferment weird in lots of people’s digestive systems. I suspect a lot of people with a ‘gluten’ sensitivity actually have FODMAPs sensitivity, but either way if not eating wheat makes them feel better then great, they know their bodies better than I do. (I have to avoid a bunch of foods for these reasons, but fortunately wheat doesn’t seem to bother me. Beans, oats, grapes, and artificial sweeteners all give me horrible diarrhea and/or constipation though, even in small amounts.)