You don't have to be glued to the screen playing with social media; it's just a tool for grocery lists, GPS navigation, getting timely updates about, say "an impromptu game night your friends want to invite you to."
To each their own; maybe your social circles are completely disconnected but even my 70+ year old parents email me through the day. I see the email immediately and can plan my day accordingly. (for example: if they've invited me to dinner, I can go there directly from work instead of detouring because I didn't see their email until I was home - several bucks and between minutes and hours saved... that adds up over the course of a month)
First part, I really hate using a cell as a grocery list. It takes way more time to type it in than write on the piece of paper and then you have to tick it off to remove the item on the list. Also, I am not the only one that does the shopping. So either you duplicate the list or you end up not having it when you need it.
I used the "Grocery IQ" app and have "favorites" set up. I don't have to write anything - I just go to my favorites list and check off "milk, eggs, tomatoes...etc" and they're added to my list. The app sorts by aisle (and you can sort by store, but I don't bother).
For me, this is WAY more efficient than finding a pen and a scrap of paper.
Regarding sharing of grocery lists between family members: GroceryIQ can be synced. When I had a live-in spouse, we shared a list... if she was picking up a few items on the way home, they automatically got check off on my list.
We shared a Google calendar too so we could plan around shared resources like the car.
To each their own.
Second part, maybe I am introverted, but I don't like being invited last minute to an event planned that same day. I like to plan ahead what I want to do in my spare time. I also don't like being available all the time via text. Each time you receive a text, you feel compelled to reply something even if it is just "lol". This is draining for me.
This has absolutely nothing to do with technology and everything to do with the human part of the equation.
I can choose to reply, or not. I don't feel compelled to immediately jump on every message that comes in. My friends know, if I'm not replying, I'm busy. I don't "play" with my phone when I'm around people, though maybe I did for the first few weeks of having a smartphone.
Humans (writ large) have not yet adapted to the technology, hence things like "nocializing" and "message anxiety." I'm sure the telephone c.1915 made people jump when it rang.