That "or" is doing a lot of work. I have an ancient nokia dumbphone on which I receive or make ~1 call per day. The effect on my lifestyle is not comparable to having a smartphone.
The largest demographic without a cell phone is the 65+ age group. Only 61% of the people in that group have a smart phone.
My guess for the condition of those people? Elderly people living in nursing homes, possibly not mentally able to learn enough to use a smartphone, or possibly happy to just use a tablet for apps and games, and a dumb phone for calls.
Honestly, if you're so old that you only rarely leave the house, then an iPad and a landline already is almost as good as a cell phone is, since you'll always be close enough to your wireless phone in your small nursing home or house, and the iPad covers all the actual uses of smart phones just fine (tiktok, whatsapp, playing candy crush, checking email... which I think is 100% of the usage of smartphones, right?)
He does have an EPIRB and paper maps though.
Sounds like you just don't meet many elderly people.
So there is this one couple who saw that my parents were using iPads and so they learned that one could use these even at their age.
Fast forward a few years and the husband of that couple is firmly into Q anon
A lot of the rest is probably older people who only use a landline, people in nursing homes, etc.
https://www.nytimes.com/2011/01/03/us/03prisoners.html
https://www.forbes.com/sites/walterpavlo/2020/04/19/will-cel...
But using a phone for the odd phone call, message, map check, translation, calendar, tickets (bus/train), rides (Uber), doesn't make your lifestyle worse, only better.
Unfortunately dumbphones can't handle even some of the more basic utilities, or if they do, they use a significantly worse interface (number pad keys) which makes it all take longer.
That states more about your self control than anything to do with the type of phone you have.