People's perceptions of what is rude or expected behavior is quite subjective within the realm of general work pleasantries. So my question to you, is what makes you feel like you are an authority on this subjective experience enough to denounce these peoples apparently very common behaviors as inappropriate? Why do you get to decide it's rude? If the world is 50% extroverts and 50% introverts than isn't it possible that maybe half or more of the people aren't taking all of these 'slights' that you are as rude but are actually finding them perfectly acceptable? Why do you get to be arbitrator of all that is socially acceptable?

I don't think my requirements for socially acceptable behaviour in the workplace are particularly arduous - be able to converse, not act rudely toward coworkers, be able to read between the lines to figure out if an event is mandatory or not without being explicitly told, attend the bare minimum of social events (during work hours, paid, exception occasions such as promotions/retirements)

My second point, is that from reading your responses it sounds like you might be addressing individuals that have characteristics indicative of being on the autism spectrum than simply introverted. It seems presumptuous then to me, and slightly overly judgmental, to assume that you know how best to help these people or that they should just be 'practicing' their social skills more. If they can perform the function of their job fine then it isn't really any of your business.

I don't believe I know best how to help someone, but I do believe that people with poor social skills can benefit from guidance. I do think a complete lack of social skills prevents someone from doing their job effectively.

I used to work with a lady on the Asperger's spectrum. When we worked on projects together, the emails she send me were borderline abusive - constantly questioning my competence, micro-managing, going over my head to my boss, telling me I was wrong and her way was the only way of doing things. When I complained to my boss, he decided to reassign us to different projects rather than discuss her behaviour with her, despite agreeing the emails were inappropriate, because "that's just the way she is". I think this is a situation where guidance on social behaviour would be appropriate - and I would note she no longer works in our field after being acrimoniously fired from her previous workplace after a falling-out with her boss.