I don't get that at all. I've been doing something like this since before the iPhone ever existed because I like having a logfile of all of my inputs and outputs, and I like being extremely mobile. Immutability means that if my phone gets smashed or stolen, I can just go buy a new one and not lose my shit. What's the thorn?
These days I think do something very similar to your friend. I pack an external keyboard and mouse I like, and a chromecast (just in case) and that's it. Not packing a big screen and a battery is just a huge bonus.
The thorn is that if I wanted to run a python program, download a mp4 and convert it or to edit a html file (all things I got hamstrung doing recently), I couldn't because the IPhone restricts access to its shell, as well as several common features in its forced web driver you can't opt out of. My phone is immutable yes, but what's the point if its immutable state doesn't do what you want it to
These days I think do something very similar to your friend. I pack an external keyboard and mouse I like, and a chromecast (just in case) and that's it. Not packing a big screen and a battery is just a huge bonus.