I liked this article. I think more about friendships than any other philosophical topic. I moved to a new city at 22 where I knew almost no one. It turns out that it's orders of magnitude harder making friends without a few seed connections. The nuances of meeting people and building relationships are so arbitrary and idiosyncratic; some things, like sports, happen to be really conducive to making friends, whereas conferences and tech meetups for me proved less fertile. Even acquaintances often simply aren't looking to change their group of close friends.
It was frustrating and discouraging for a long time and then suddenly I found myself with people to call on and spend time with. Half a decade later I moved and had the opportunity to try the experiment again. This time secondary connections made finding my network almost trivial. Maybe age helped too, being further removed from the university cliques.
I was relieved to find out, albeit way after the fact, that many have this experience. One friend recently quit his job to start a company focused on this phenomenon [0]. I hope he can displace the zombie of Meetup.