Dinkelbrot

Hello, I have noticed that a lot of Migros breads contain rye flour. This spelt bread is no exception. Can you tell me why this is the case? Is rye flour cheaper than spelt flour, for example? Why can't this bread simply be made from 100% spelt flour? The background to my question: Like many consumers, I am sensitive to FODMAPs. In other words, it gives me bloating, stomach ache, flatulence, etc. Rye flour contains many times more FODMAPs than wheat flour, and the latter contains more than spelt flour. I can tolerate spelt bread and sometimes also wheat bread (depending on the quantity) as long as they are pure. But as soon as it contains rye, I get symptoms. It's good that I can find pure spelt bread in the village bakery, but also at the Coop.