Modern wheat durum wheat has a far far higher percentage of gluten than the wheat of
earlier centuries--it's a major change.

And modern bread made by the fast factory Chorley Wood process
is also very very different from the bread of a century ago. The high-speed rise
and various additives mean that the wheat is far less broken down by fermentation
than in traditional processes.

If you are skeptical about non-coeliac gluten sensitivity, consider the interesting example of
people who report that slow-fermented sourdough bread agrees with them much better than other types. In slow-fermented breads with wild yeast, the gluten has been much more broken down by the action of the yeast than in fast-process bread.

The changes in wheat and bread due to modern production and selection are huge.

The intestinal microbiome also varies hugely between individuals...