It helps people with IBS to cut down on gluten too. I think it’s because gluten containing grains also contain fructans, which are banned on the Low Fodmap diet.
IBS often includes gut dybiosis issues (imbalance of gut flora) and some of the consequences of gut dybiosis can be foggy mindedness, attention problems and skin issues (as well as digestive distress). So cutting back on any food that exacerbated the dybiosis could make a difference there.
There is increasing evidence that some people with (post-infectious) IBS actually have a parasite called Blastocystis Hominis. Not only does this cause gut dysbiosis, but there’s also evidence that foods high in phytic acid and lectins cause the parasite to release an enzyme which causes the IBS symptoms (spasms, digestive distress etc). Grains are one off the key trigger foods there ( so are pulses and seeds, also fruit and veggie skins). So as a gf diet can cut out a lot of grains, it could help in that scenario too.
A lot of gut issues are just beginning to be better understood now. There are links to lots of MH conditions for example. Conditions like IBS have been diagnosis that actually cover a lot of different conditions, which are just starting to be unpacked and understood now.
So, yes, it’s looks totally possible someone who’s not coeliac could benefit from cutting out gluten. That’s without going into non-coeliac gluten sensitivity, or other auto-immune conditions like Hashimoto’s.