Again with the anecdotes but a good friend of mine does exactly this. He's not a tech enthusiast and hasn't owned a computer since I've known him. His wife has an old laptop but he doesn't use it and isn't familiar with it.
At some point in the past couple of years he wanted a smartphone after seeing all of us using ours for instant messaging, Instagram, etc. and he chose an iPhone specifically because they have a reputation of being user friendly for even the inexperienced user.
His phone recently ran out of space due to the large number of photos he had taken so I advised him to hook it up to his wife's computer and use iTunes to back everything up. He looked at me like I had three eyes. Up until then he had never done this. Everything came over the air and he treated it as a standalone "appliance".
I did my best to walk him through it and stress that he might want to get a Dropbox or Google Drive account for some level of redundant backup since his wife's laptop isn't what I'd call reliable. As far as I know he sort of glossed over when I got to that second part but at least he managed to get his phone working again. It had actually gotten to the point where things stopped working due to lack of available storage.
True, but Apple has advertised "PC-Free" as a selling point of iOS devices since they rebranded iCloud in 2011. Theoretically the device should function perfectly fine as your sole computing device. I suppose their solution to this problem though would to have a larger storage option.