To me, it's opting into different means for keeping in touch and hence, keeping that "presence" in my friends' lives.
I quit Facebook a year ago - I had 800+ friends. I was only "close" (subjectively) with a slim fraction of that. Now, I text, call, send birthday cards, and use other means to communicate with those I truly care about. Not that I don't care about the other, it's more of my way to prioritize the people who I've shared more life experiences with and/or can better relate to.
If I see the others who aren't in that close circle, we have plenty to talk about. If I see my close friends, well, we do as close friends always have done.
No offense, but I would argue the notion of needing "presence" in people's lives contains some inherent narcissism which is also prevalent on social media; and to be fair, the other piece is the need for belonging. True, it was a tough pill to swallow when first disconnecting, but over time this faded and via the other means I suggested, I've found I get that same level of belonging.