Hair on your neck makes you look unkempt. I think it's the main issue.
* rejecting other personal hygiene customs
* being noticeably more pedantic
* picking every battle/argument
* lower than normal respect for other's boundaries
* lower than normal awareness of how their actions effect others
* making "being rational" a core part of their identity
* dismissing human behaviors they don't do as irrational. usually these are the ones where rational explanations do exist, they are just difficult to re-invent on the spot.
This package is common enough to have earned itself a name, which happens to be the easiest visual indicator.
Oh, and every single person who has hair on their neck looks unkempt, without exception, am I hearing that right?
Sure, OK.
Yes, shave it. Especially if you have long neck hair and short or no facial hair.
There are some exceptions, if you have a long beard, maybe.
Hair in other places is considered equally distasteful (long nose hair, ear hair, whatever).
...by some. Clearly others disagree.
Personally, I like hairy men and women. It's a clear sign that I won't have to deal with some priggish prude who is more concerned with looks than personality.
Ok, but don't be shocked if some of those priggish people avoid you and unfortunately for you, they may be the ones deciding to give you a loan, to go on a date with you, to offer you a job, whatever.
Everything in life comes with trade offs.
And sometimes it's not worth winning the battle to lose the war.
Everything does come with trade-offs. That's correct.
Being well-traveled is a cure for bigotry though. Realizing that you're in a bubble is the first step.