Endpoints not being able to connect to each other makes some functionality costly or impossible. For example, peer to peer distribution systems rely on being able to contact cooperative endpoints. NAT makes that a lot harder, meaning plenty of development and usability costs.
A more mundane example is multiplayer games. When I played warcraft 3, I had lots of issues testing maps I made because no one could connect to games I hosted (I was behind a university NAT, out of my control). I had to rely on sending the map to friends and having them host.
For example, peer to peer distribution systems rely on being able to contact cooperative endpoints.
Unlike what the TCP/IP designers envisioned, current internet is basically client/server. A client always initiates the exchange and should be isolated from unsolicited access. If necessary, P2P access is a solved problem, and it is properly done by applications at a level higher than TCP/IP, anyway.
no one could connect to games I hosted
Arguably the university's NAT functioned as intended. They did not provide you with internet access for the purpose of hosting games, even if they weren't actively against it.
At LW London last week, someone mentioned the possibility of a Google Glass app doing face recognition on people. If you've met someone before, it tells you their name, how you know them, etc. Someone else mentioned that this could reduce the social capital of people who are already good at this.
A third person said that something similar happened when Facebook started telling everyone when everyone else's birthday was. Previously he got points by making an effort to remember, but those points are no longer available.
Are there other social skills that technology has made obsolete? And the reverse question that it only just occured to me to ask, are there social skills that are only useful because of technology?
I'm not really sure what sorts of things I'm looking for here. "Ability to ask for directions" seems like one example, but it feels kind of noncentral to me, I don't know why. But I'm mostly just curious.