Most apps require constant updates or they stop working.

I had set up my iphone to only update on wifi, and was travelling for a month or so only using mobile network.

When I tried to get an uber, I realized the app didn't work correctly (the driver appeared to be in the middle of the ocean). Same for other apps.

Games and apps that don't use heavy server code work fine, but google maps, uber, whatsapp, facebook, and some of the KEY things will break eventually if you never update them.

Once my bank forced me to update. When I went to make a “scheduled payment” (as I like to do after opening my bills...), it now said “coming soon”.

I was not impressed.

Google maps probably won't break, but other things might.

https://beebom.com/google-maps-backwards-compatible/

It was quite a while ago but IIRC it was around the time of a major iOS update (which I had done) and so in the days that followed many of the apps “required” an update which I couldn’t complete. I wish I could remember which app needed updating that finally pushed me to add my credit card as a payment method. But here I am two+ years later and that AmEx is still the card associated with my AppleID rather than my debit card.

I've had my debit card replaced and forgot to update Apple's payment details

The phone might as well be bricked, updates fail and constantly pop up the payment screen, can't install new apps.

It's like having a virus on your phone.