someone who says "i'm allergic to gluten" has self-diagnosed and is an idiot who doesn't know what they're talking about

I'm claiming this because gluten allergy is so rarely diagnosed that we don't even know if it actually exists. So yes, they are probably wrong. It is possible that gluten plays a role in wheat allergy but it isn't conclusive.

you're tilting at windmills to feel superior to people with real food issue

Or maybe it's because a tablespoon of an allergen can kill someone. Would it make sense to start talking about ebola and the common cold interchangeably? We're not talking about eating something and feeling a little sick afterwards. I had an 8 year old patient die last year because her babysitter didn't take her diary allergy seriously and I've had many others end up in the ER for similar reasons. This has become vastly more common since the anti-gluten fad started and the word allergy basically become a fashion accessory. This trend negatively effects people with Celiac disease also by the way.