The main benefit is really just having more free time, focus and attention that you can channel into things you actually care about. So if anyone needs motivation to un-tether, think of it like this: being a phone user cuts your life roughly in half (in terms of the portion of time that's actually available to you to use).
I could go even more extreme on the phone decoupling, for instance I still bring it with me if I'm going to a bar or something, but at the moment I'm more focused on whittling down social media usage on computers as well. It does feel like the endgame could be a better life through just abandoning most of the tech that was cooked up in the last 15 years.
So I think about carrying a flip phone for my telephone, an e-reader for entertainment, and a smartphone in airplane mode for (mainly) maps, photos, music, notes. But then I'd be carrying three devices, which seems worse in its own way.
Probably worth the change ultimately?
It seems like it'd be ideal for the backcountry use-case. Super long battery life because you could just wake up the GPS every few hours and get a new fix, reframe the map, then go back to sleep and use the latent image like a topo map.
I never had a big relationship to my phones simply because I can't stand typing on them. My plan (prepaid) is 1€/month for 1GB and 9cents per min/SMS.
I think there's a lot of gains to be made in tailoring UX/UI to the individual. Not just for individuals (this person reading more books) but for societal advancement. (this person reading more books, generalized)
How do they do 2-factor auth to Heroku/Gitlab/whatever? Maps in a foreign country where you can't even read the letters? On way to job interview when the interviewer has an emergency and needs to postpone? Good friend is in the town and calls you to hang out? Translation when a tourist comes to ask where something is?
Been four years since I had cell service or regularly carried any internet capable devices and I have never been happier.
My anxiety has plummeted and my attention span and productivity have skyrocketed. I do not have a phone as a security blanket anymore and feel so much more confident in public.
Smartphones are optional for most people, but if you are forced to carry one, keep it in airplane mode whenever possible and only use it when solving the specific problem that forces you to carry it that you lack any alternatives for.
If you need mobile entertainment buy a paper book.