I think it is because some people are pushy hosts. These are usually heavy drinkers themselves and it gives them a reason to fill up their own drink while they are making you another one. My husband is and my father was like that.
You know, I'm not much of a drinker. I don't have any kind of moral problem with it, just never found anything I really liked that much. I've never felt guilty about saying, "No thanks. I'd rather have a Coke."
This is why God created potted plants! When I'm confronted with someone who take "No" for an answer, I accept the drink and then either abandon it, pour half of it down the sink or give the nearest pothos a slug.
Oddly, it never seems to harm them.
You're right. Also, misery loves company. Plus if you are around someone else doing "wrong" you don't look so bad. It's awful. I hope everyone enjoys the holidays without wrecking their good sense and good habits. I know it can be so hard. Let's be strong and remain true to ourselves.
I had to get away from the mindset that I needed to apologize myself away from a drink. I also avoid those type of parties. I decline the drink, and offer no explination. I don't owe anyone a reason for my abstinance. Even if asked I still offer no reason. I'm friendly the first time I decline, but if they push it they have just squared off with me. If they want to be an A$$hole about it, so can I. I don't want to be, but I feel I must have firm boundaries in this area and they are not negotiable. Insistance is an intrusion.