Yeah, that checks out - some variety of this line of questioning plays out every time I have this conversation, so it's just about time you got here. Let's see if we can save some time here:
"Your friends must be terrible people!" - no, as we've already covered, they're not. They helped get me through some rough times. Terrible people, and I've known my share, don't bother.
"Well, then, you must be a terrible person!" - if that were the case, the apologies I got wouldn't have happened, much less been heartfelt. They weren't snubbing me on purpose, or deliberately cutting me out. I've seen my share of that, too, from both sides. This wasn't it.
"Well, then, what you're saying just doesn't make sense!" - sure it does. We're all busy professionals, no longer young, many with young families, all with significant demands on our time and mental energy. People drift apart, it happens. That's probably what it looked like, from the perspective of people on Facebook: me drifting apart from them. In a sense, I suppose it's even true.
Just that it didn't happen that way because I wanted it to, or because they wanted it to, but rather because Facebook wanted it to. Because as you grow ever more accustomed to communicating with everyone you know via Facebook, it gets ever easier just not to think particularly about communicating with anyone any other way.
There's an activation energy barrier to everything, not just to joining the mailing list for some SaaS startup. The more you get habituated to Facebook, the higher that barrier gets with everything else by comparison.
And eventually you get tired of feeling like you're carrying the relationship, and tired of feeling stung by hearing after the fact about another fun camping trip or dinner or wedding that you didn't get an invite to because the whole thing was planned on Facebook. Eventually you just give up, and maybe it takes a few years to realize that you weren't at fault, and neither were your friends. You both got screwed out of each other's company by a machine that is designed to do exactly that, because it can't make money from social interactions that occur outside its hegemony.
That's that punishment I was talking about. It isn't a metaphor. It is a consequence imposed by design to convince Facebook abstainers to do otherwise.
And to forestall your next objection, no, I don't think anyone sat down and planned it that way - probably not, anyhow; I don't put much past Silicon Valley, these days. But even if it's an emergent property rather than an intentional one, that's still no excuse. The purpose of a system is what it does. And this, again, is what Facebook does.
Anything else?