While statistics indicate that 1% have Celiac disease, there is much room for error in the testing. Many doctors do not tell people that they need to “load up” on gluten before the test to get an accurate reading.
In addition, the number of people with Non-celiac gluten sensitivity is easily 6x greater than the number of people diagnosed with Celiac. While they don’t have a doctor-administered test for it yet, there is an organization working on it. (too lazy to find the link, sorry)
Both Celiac and Non-celiac gluten sensitivity affect the villi, which is turn can also cause or exacerbate lactose tolerance.
So until there is widespread availability of the type of “ancient” grains our great-grandparents ate, many people cannot afford to rethink going gluten free.