It's also super nice to take notes on the fly for OpenStreetMap with StreetComplete, for holding the device up to the sky and it tells you what planet is so bright in the sky, for navigation... These things don't work on a laptop. Even if you want to carry a full-sized system in place of a smartphone, or use Ubuntu Touch, I'm not aware of software to do these things in the convenient way that Android apps let you

Of course, that's a software support issue and not a constraint imposed by the OS. Someone could make Stellarium desktop work with an orientation sensor. It's just that nobody has done that particular thing, as well as a million other things that work super well on mobile

So is it second-class, or is it just a way that is optimised for output rather than input? You get the turn instructions presented to you, you can watch videos and listen to music, note-taking is optimised to work with a few taps and is reduced to the essentials you need. You can work them out later on computer if you have time at home over of course, but at least you can contribute that way with ease