It's not that the author didn't get to chat about people's lunch on Facebook every morning. It's that the author wasn't invited to things he should have been invited to because to many people, "I invited everyone from my FB list" sounds like they invited everyone they reasonably could. Which is not true. The author explicitly says that he is easy to find. And his school friends should take the extra several minutes to searchengine each person they didn't have on facebook if the event is relatively big and organized. It should be the default response. And the author is rightly frustrated that it isn't, because people are lazy and can unintentionally be careless.

That isn't comparable to not being invited to a spontaneous dinner in 2 hours at 9PM by someone clicking invite all of their contacts list tagged as classmates because you're living in the mountaints a one-hour flight and a two hour hike away without any communication tools around you and you don't even believe in flights.

I don't mean these examples to sound flippant, they're here because I'm trying to underline how there's reasonable compromises between convenience and being a good friend / event organizer, and not being on facebook doesn't make you hard to contact. It definitely didn't in the case of the author.