I was not on Facebook for years, it didn't add value for me at the time but did add lots of potential for conflict and argument with my SO. We're separated now and I've been flying solo for a bit, so I've logged back in and have been enjoying it. I was very isolated in that relationship and down to my last two friends which is where I drew my line and I think a big part of why she left (and tried to clean me out too!), because I wouldn't ditch or put at risk my last friendships to please her.
In any event I've reconnected with several old friends who I would otherwise have not have, we've met in person and done things together. I also use it for groups and events, to find things to do to go out and be social or stay connected and current with groups (that regularly meet in the real world) and upcoming events. I dislike that it has become videos about nothing, videos where pictures are more effective, or pictures where text is more effective, but I unlink people who post those things frequently to minimize the nonsense I see without looking for it. So for me getting back to social media has been great, it keeps my busy with real life activities and helps make real life friends, as well as occasional entertainment if I'm lonely or bored and too tired to go out and do something.
I think deleting social media would be isolating for me. Maybe not a big deal for those married or with kids and your own settled social circle... But that was not my situation when I logged back on.
As for twitter and instagram... I don't think I'm old, but maybe I'm too old to "get it". I don't see how one sentence or pictures only are an effective way to communicate. I have no desire to partake in those.