"But why? If to make this system work you need the bulk of a wireless keyboard and mouse, you might as well carry a stick-shaped Linux computer."
Different use cases I suppose:
1. Keep the big peripherals at home and use the phone as a phone elsewhere.
2. Carry a keyboard & mouse in luggage. Trade-off keyboard size vs convenience* to personal taste.
3. Hot desking - a keyboard, mouse & monitor will be available in a remote office & carrying a phone is more convenient than a laptop.
There are probably takers for each of these. You might not be one of them, it doesn't mean everyone has to follow you.
*I used to have a Nokia Communicator, a clamshell tending to the size & weight of a brick. The keyboard was quite tichy and so was the 80x24 screen but back then you could get away with hanging a modem off the back of a computer so I did remote admin with that with no real problems. Eventually I replaced it with the next generation wich was smaller - big mistake. But for some reason I can't really get along with on-screen keyboards, even on a tablet.