Plus, with the right combination of applications (more preferably, a few, and some with no active internet permission at all) and power settings tweaked both for better battery mileage and longer, more focused on-the-go sessions (e.g. editing documents, playing that one dungeon crawler roguelike, and planning important events, etc.) you could count on it more.

This is really the only answer. If you think being able to put your your desktop in your pocket and use it anywhere would be useful, then you’d probably find a smartphone useful.