I think this happens with other things too.
Take diet as an example. When I was a vegetarian, I couldn't go a week without someone saying something sort of snarky, "Oh, too good for beef, eh," or, "What's your problem with hamburgers," or, "Mmmmmm, so juicy and meaty (with added tone and body gestures)". Keep in mind that I didn't feel righteous and I wasn't doing it to prove any points, I just didn't want to eat meat.
Entertainment can lend as another example.
"I don't watch horror movies,"
"Come on, you'll be fine, just try it this one time,"
"No seriously, I can't handle them,"
"Oh, come on, don't be so dramatic",
or
"I don't watch television,"
"Why not,"
"I just don't,"
"How 'bout your kids,"
"Nope, not my kids either,"
"Oh, so you're one of those people who don't let their children have a normal childhood."
I think it's human nature to think
- Our way is the only/best way
- To be threatened by other ways and perceive other ways as an implication of our own ineptitude or flaws.
And then, there are other reasons too. I grew up in a first generation home and hospitality was taken very seriously. When someone comes into my home, it actually pains me when they won't accept food or drink. I've been taught that you offer again and again, until a person relents. Likewise, you decline any offers that might be received, and the host then pushes you to accept. It's a little cultural dance routine. This is tricky when I'm with people who grew up differently because the tradition I recognize as polite, could come across as overbearing/pushy.
And then, of course, we have our drinkers who have an unhealthy relationship to alcohol. It's funny, with relationships (people, places, or things), we often want company. So if I'm overdoing the sauce and feel guilty about it, I might feel slighted or shown up by you if you show a tendency towards moderation. I might feel better about my 6 shots if I see you take at least 2. Birds of a feather / misery likes company / denial...that sort of thing.
I'm a non drinker and have the odd uncomfortable moment when I have to turn down an invitation to drink, once, twice, thrice. I find humor is the best lubricant in these situations. A joke puts everyone at ease AND gives me the ability to set an assertive boundary.