I find the dairy-free, gluten-free crowd (e.g., paleo, etc.) to be at least equally annoying (people with legitimate dietary restrictions like celiacs and lactose intolerants excepted).
From my observation, they tend to be at least as dogmatic about their dietary views as your average vegan.
I'm like, "so anything introduced into the human diet subsequent to the advent of agriculture or domestication of animals is per se unhealthy? I'll try to remember that the next time in Phoenix in July and am tempted to turn on the air conditioning."
To listen to one of them, I might as well put my affairs in order and have someone write up my obituary if I dare eat one bowl of: