18% of people are following a food trend. Within that 18%, there are two groups: a group of people who have a psychosomatic illness, and smaller group who are sick, but empirically not adversely affected by gluten.
Before this study, there was a single study containing evidence that gluten restriction might help some people with persistent bowel disorders.
After this study, there is no longer any scientific evidence that gluten -- the actual protein -- adversely affects people who do not have celiac disease. The studies demonstrating otherwise come from both ends: both gluten trials against people who think they are gluten-sensitive, and gluten-free trials against people who have bowel disorders of no specific etiology. When the amount of gluten they ingest changes, former group don't deteriorate, and the latter group don't improve.
Of the people whose lives appear to be improved by glute-free diets, the consensus position is that their gut flora are responding to indigestible sugars common to grains and other foods: the fructans in wheat and rye could be the reason that gluten-restriction appears to help those people. This research substantially predates the gluten-free fad: there's plenty of solid empirical evidence, going back twenty years, that cutting FODMAPs helps people with a wide spectrum of bowel disorders.
If this is the case, the people to whom Whole Foods has marketed illness-as-lifestyle-choice are likely to be made ill by unrelated things like artichokes, eggplant, and mushrooms. For those people, gluten-free diets are a stopgap: for instance, spelt (which makes perfectly fine bread) has lots of gluten and very small quantities of fructans; artichokes contain large quantities of fructans and no gluten.
As long as people keep insisting that the explanation is gluten, and as long as the evidence continues being contrary, a substantial number of people who are sick will never get any better. This is the problem with letting marketing get out ahead of the research.