You can't email someone 13 hours away? [0] What difference does it make if they're spread out all over the globe or not, whether you can email or FB them?
I do get the idea, sometimes I feel a little bit excluded without an FB account, but I have never had the problem that somebody didn't have an email address. Not even kids.
People seem to make up all sorts of excuses, but in the end it always boils down to 1) suffering minor inconveniences and 2) the (often[1] irrational) fear of social exile.
As other people have pointed out, changing networks is not that hard. It's a false belief that it is. Years ago my local friends were mostly on MSN[2], East European/Middle East folks were on ICQ and Y!C, US people were using AIM. So I used Trillian and later Pidgin. What you saw was this, people are moving around all the time, and many of the persons were 2 or 3x in my contact list because they too were on multiple networks. Google chat just sort of edged itself in there as well.
Think of it like this, remember how easy it was to find all your friends on FB because of that network? And didn't the same happen with email, and with AIM/MSN/iCQ/etc? I see friends and acquaintances trickle in on G+ without any effort for that reason (except I don't want to use G+ either). Now FB pushes its "help" quite aggressively, but even without that, people connect in networks, point eachother to their friends, it's very peer-to-peer :)
[0] I mean, it happens ... http://www.ibiblio.org/harris/500milemail.html
[1] note I'm not saying "always", I can imagine certain high school scenarios where this fear might be somewhat real, although one has to wonder ...
[2] unfortunately I lost my MSN acct because the not-hotmail domain I registered it to expired a long long time ago and it stopped working--if anyone knows a solution to that I'd love to hear it because I would love to see that old contact list back :) (however I could also reg a new account and repopulate my contacts via-via just as easy)