This is the gulf UX design is supposed to cross, I guess. Designing for people who engage with tech in utterly different ways to me.
On the one hand, I rarely use my smartphone at home because I have computers.
On the other hand, I hear stories from parents at work whose kids don't want a computer because "Why would I need one? My phone works fine."
I’m 40 and if I wasn’t a software engineer I wouldn’t own a desktop / laptop computer. As you say, what’s the point? Everything except for software development can be done on a smartphone. Why even bother installing an instant messaging application on the computer when you can just take the phone out of the pocket instead of walking to the room where the computer happens to be? Even when I’m working at the computer I use the phone for music, messaging and news.
That sounds like a little too broad a generalization.
A typical office worker who creates or consumes documents, presentations, accesses corporate apps (half of them still 90s tech with lipstick), submit proposals to clients, review others' work, attending multiple hours long zoom calls with screenshare, etc ... are still using at least 13" laptop screens to do a lot of their day to day work.
Sure a sales executive or a senior manager might get away by just typing one liner commands to minions on their smartphone, hitting approve buttons on expense apps, and just listening into team calls, etc. -- but lower in the hierarchy where the real numbers and usage are ... we still have physical keyboards and mice, and decent sized screens (often multiple monitors) to help us stay productive.
More and more people, particularly the younger generations, don't have anything besides their smartphone because what's the point? It's additional expense, additional maintenance, additional clutter, additional mess.
They can do everything they need on their phone.