I grew up without one, but came in fully to the working world of 'always on'. It took me 6 months of 'non corporate work' to get used to the idea of not receiving emails all the time. It becomes part of your identity and you feel lost without it. But then you regain something lost - peace of mind. I can't even imagine what it means to grow up 'fully connected' - sometimes I think that young people must be excessively…
Not using apps is way more radical than blocking almost all notifications.
Even the possibility of getting notifications is stressfull.
The difference between having a phone on, where people can contact you - vs - phone dead or 'no phone' is definitely noticeable. 'Knowing you don't have to check' is an extra level of peace.