I was navigating a big city and the surrounding countryside at the age of 12 before the internet was a thing. Apps and phones are not necessary for exploration.
I did not say it's necessary, but it's a HUGE improvement to moving with transit. You cannot change at the last minute unless you know all the bus routes, which you can do with a map app.
It makes an enormous difference for transit.
Knowing when the bus is arriving allows you to decide to walk. Not every places has buses that arrive on time. In Rome a bus can be late by 40 minutes, in which case walking is an option, especially if you are young.
