How do older people end up with social skills that are no better than mine?

I know I have no place criticizing people's social skills because I don't have that many myself. Normally when I encounter someone who is socially awkward, I see where they're coming from and we try to muddle along.

But it occured to me that my social skills have been improving over time. I see someone use a formula I could use, so I yoink it and use it myself. For example, I used be awkward about leaving voicemails asking people to do something specific - I never knew how to end them smoothly. Then someone left me a voicemail saying "...so if you could get back to me on that by the end of the day, that would be great. Thanks!" That would totally work! So now that's how I end my voicemails. I do that whenever I see someone do something that would be a solution to a problem I have, and I'm slowly improving over time. It isn't anything deliberate, it's just the normal process for diffusion of linguistic innovation.

But I know people who are far older than me and don't have much better social skills. They can be like twice my age, but they don't often do better than me and in some cases do worse than me.

How does that happen? Are they not improving, or were they worse than me to start? If they were worse than me to start, how did they get jobs? And I'm not saying that snobbily (I've only had one good interview ever myself) - I know there's a certain amount of charm required to do a successful job interview, even for a position that isn't big on people skills, and I can't imagine that a person with my people skills minus 30 years of experience could do that. Did job interviews require less charm 30 years ago?

Or is it possible that society's people skills in general have improved, and any given individual stays in their place within the hierarchy? It might work that way, since everyone is probably improving the same way I am. When I'm 100, kids are probably going to look at me and wonder how I ever functioned in civil society.