Fully recognising that you said "IMO", I'll say that keeping up with acquaintances and people from the past is normal in my culture. Social media helps to make that more direct and easier to manage than the gossipy grapevine of yore.
What's normal depends on your culture and context, of course, and I suspect that's not true in yours — but it is in mine, so ditching something like Facebook is just out of the question for me and many people whose cultures place a heavy emphasis on those connections between people.
The middle ground for me has been to check Facebook less and less, accelerated by the algorithm delivering me fewer life updates and more slop reposted from reddit.
There are lots of things in the world where the work required IS the value. Think of a hand written note from your CEO; is it still valuable if it was their assistant and a picture of the signature? "keeping in touch" is not inheriently valuable; it's the effort required that makes it so.
It does seem quite normal now to keep up with people you haven't seen in 10 years in person and will never see again. Maybe even people you would go out of your way to make sure you don't see in person but you can give them a thumbs up when they post a picture of their lunch.
I have no idea why anyone does this but it would be hard for me to say that not having any social media like us is "normal".
Our people barely left our homelands, our pā and marae, for fear of them being stolen by pākeha-let governments who urbanised the rest of us into poverty.
Now that people in my culture are reconnecting with the importance of whakapapa for whānau, hapū, and iwi, which is a far wider set of people than just one’s immediate family in typical anglospherical thought, there has to be a way to reincorporate all the urbanised people who live far away. Social media, at least initially, provides that.
But thank you for your “is your culture only 20 years old” crack. It’s always refreshing to have the needs of my culture explained to me by someone from without it with an air of armchair authority, as though I or we don’t know what’s good for ourselves to meet our own needs.