Yeah there's a difference between straight edge and super straight edge types. The latter can border on this pathological tendency to look for negatives on anything enjoyable to find excuses for why it's bad. You'll see it in various people for reasons for total abstinence from things. I think a lot of it is caused by anxiety, so it can end up manifesting in a lot of different directions rather than just someone avoiding one or two things they personally have issue with.

Naturally it's fine to abstain from smoking or drinking or anything you want, I'll even say it's a healthier lifestyle choices (physically but not necessarily socially) but you'll eventually meet someone who just abstains from basically everything you can imagine and they are very difficult people usually. I believe the proper term is wet blanket? You go out with them, order a beer, they'll start complaining about how alcohol is bad, order a coke instead they'll complain about sugar is bad, order an ice water they'll tell you ice is bad. There's no end to it. The only acceptable order ends up being a plain salad with romaine (iceberg lettuce bad! Too many carbs!) no dressing or croutons (cause gluten bad!) and a side of plain room temperature water. This is from personal experience.

I think it's the same basic problem with vegans, nobody cares if you personally want to only eat plants, but once you start suggesting that others should only eat plants and get short towards the people who don't follow your own life choices it gets nasty quick. Same with the militant anti-tobaco people who whine about smoking zones existing and demanding it be banned even in adult establishments. Same with the militant plastic bag police in line behind you suggesting you don't really care about the planet because you didn't bring your own.

Basically, they are almost always judgemental busybodies.