This is an interesting thread.
I’m coeliac and also have Crohns, although it is in remission at the moment. I did the SCD (Specific Carbohydrate Diet) and it worked really well for me. I don’t follow it to the letter now – I include some white rice, potatoes and sweet potatoes in my diet, but I generally try and limit my grain consumption.
I go back to the SCD if I have any signs of a flare up of digestive symptoms and also take Intestaid IB which is brilliant for irritable bowel type symptoms.
There is some evidence to suggest that people with digestive issues do not digest grains as well as others, hence why there is some relief to be had from diets like the SCD or Paleolithic diet.