I don't think its really comparable. The difference to ultrasound sonic attacs is that celiac disease actually exists, but is very rare. There are clinical tests that can be executed, and the symptoms of it are also not quite uncommon. so a bit of confusion in this regard is understandable.
> celiac disease actually exists, but is very rare
I wouldn't call a disease that affects around 1% of the population "very rare".
It's true that there's a gluten-avoidance fad that has drawn in lots of people with no medical justification, so that not everyone who demands gluten-free food is necessarily a celiac sufferer. "Gluten intolerance" seems to be a fashionable ailment these days, with perhaps varying degrees of validity (and potential confusion with other issues that may have similar symptoms), but sources suggest that around 3 million Americans, for example, really do have celiac disease.
What is 1% if not very rare? Yes there's a lot of celiac folks around. There's a lot of people, period. The fact that there are 3-4 million celiacs in the US does not discount the fact that there are 330+ million folks without it.
There's nothing wrong with describing a rare thing as rare.
To many laypersons 1% seems like a small number. However when dealing with large numbers 1% is not at all rare. I don't know much about celiac disease, however to put that into perspective, that means that there are 4 times more people with celiacs disease than there are software developers in the world.
