This captures perfectly my reasons for getting on Facebook in ~2007. One of my best friends had a baby and I was the only one who didn't know because I wasn't on there. I'd also been one of the last of my friends to get a cellphone 3 years before, and was starting to worry that I was just a jerk about keeping in touch.
It's really interesting to compare those two decisions now. The slider phone I got in 2003 was nothing like what we have today, but buying it let me participate in a communication ecosystem that's still evolving fast.
Facebook feels really stagnant by comparison. Its core mechanics, at least the ones I care about, are unchanged. Everyone's usage of it long ago stagnated into the same patterns. I still check it because I have to for life events, but it's not something I look forward to.