What's a Social Difference And What's A Social Weakness?
One unanswerable question when it comes to social skills is when are particular traits a legitimate weakness, and when are they just a difference from the norm? Social skills are ultimately relative and subjective after all. I think some traits do fall into one clear cut category, but even then some people may have their own opinions.
For example, if someone is extremely rude and condescending, or totally lacks knowledge on how to make friends, I'd say that would be a true weakness, and something they should probably change. On the other side, I think if someone just likes to spend a lot of time alone, or has uncommon hobbies, or prefers to do quiet, low key things during their leisure time, I'd say that's just a difference, and isn't worse or better than anything else.
A lot of social traits fall into a subjective middle ground though. Like what if someone is really quiet, to the point that they often get overlooked in conversations? You could make arguments for each side. On one hand you could say not everyone has to be talkative, and some people are just naturally more reserved and like to sit back and take everything in. Someone else could reply that an excessively quiet person is selling themselves short and missing opportunities to make connections and meet people.
Like I said, there's no one right answer. Here are some questions I think it's good to ask to decide whether a trait could be thought of as a difference or a weakness:
What does the person who has the trait think about it?
This is what it ultimately comes down to. Do they see their social trait as a weakness or just a variation? Like I just mentioned, I view preferring more alone time as a difference, but some people may see it as an issue they'd like to address. There are quiet people who see it as a cut and dry problem. They want to be more talkative. They don't like how it often leads to them being ignored. There are also quiet people who are totally fine with being that way. They're okay with not being the center attention, and being more of an observer.
Is the person with the trait getting what they want out their social interactions?
Do they feel that trait is holding them back or preventing them from getting something they want? Some quiet people may feel they have a good group of friends and an interesting life. Others think of them as quiet, sure, but they still feel included and accepted by their social network. Their quietness doesn't really affect them, aside from getting the the odd annoying remark about it from people who don't know them as well.
Other quiet people may feel they're missing out. They may feel like people pass them over as possible friends because they don't say enough. They may feel left out or disposable. They may have opinions and jokes they want to share, but can't bring themselves to do it.
What do other people think of the person's trait?
Obviously someone can't just go along with every last thing others want them to do, but I think other people's opinions can be a source of information or feedback. It's then up to them to decide how they want to act on those opinions. For example, say someone keeps to themselves at their job, to the point where their co-workers often mention it and ask them why they never eat lunch with anyone, or join them for drinks after work.
One person may take that feedback and conclude, "I'm just here to work, and I'm not social like that. I understand where they're coming from, but that's just not me. It's nothing personal against them." On the other hand, it's possible they could go, "Hm, I know I like to do my own thing, but I didn't realize I was coming across as totally indifferent to everyone. Maybe I'm going a bit too far with it. I'm still going to have my own space, but it wouldn't kill me to join the others every so often."