As far as teaching your kids to talk about sports, I think it would be more just teaching them that if they don't know much/anything about the subject, they get a lot further by not being rude about it or saying they hate it. Kind of a social nicety thing. Not like you have to sit by for hours while people talk about it, but being able to listen to the conversation for a bit isn't bad. And also, if they understand a bit but something comes up that they're confused by, they can potentially ask, because people like explaining things they are interested in. (On the other hand, this may vary for guys. My experience as an adult woman becoming more interested in football has been that guys are more than eager to answer any questions I have, but a boy or man who asked some of the questions I've asked might just get made fun of.)
I think in the context of the OPers question, being able to carry on a basic conversation about the major sports is just part of it, if you are male or female, esp. if you are a female who wants to be "one of the guys" in a business meeting.
No one can know everything about every team for every sport, and asking questions IS polite. My DH's current projects have him spending a lot of time in Canada, so he is very up on Canada hockey right now. This certainly isn't something he grew up with, and he has learned a lot by asking questions and being truly interested.
And it does help in difficult business situations.
And the women who make it in his field can drink beer and talk about sports. It's cultural literacy. This is what culture is now.
And my point when I brought up sports was that if you are wanting to help your kids be socially and professional successful, teaching them to carry on polite conversations about things like sports is one of the things you could do.
But I agree that being able to engage a wide variety of people on a wide variety of subjects is really key -- my DH's boss, who has about about 2,000 people under him, can carry on a conversation with ANYONE and make them feel like they are the most interesting person to talk to. He can even do this with my DD who has autism, and he is one of the few people who can. He is also amazing at his job and consistently works 80 hours a week, but his strong social skills have been a tremendous asset to his career. If he were just as smart and hardworking without the social no-how, he would be a project lead making a fraction of the money.
I'm still pondering the question of what upper middle/ upper class people own, and I really don't know. We are in that group, but got here by moving a lot for promotions. And we have cats. So the things we once had that were breakable are long gone. The families I know with more money are quicker to buy their kids the latest/greatest gadget, but plenty of people who are really tight for money seem to come up with the money for Kindle Fires/iPads/ etc.
(I know more people live like they have money than who actually have money)