I've never understood the point of the alleged "all-in-one" desktop. It's not "all-in-one". It's still a monitor with a separate keyboard and mouse.
A laptop IS all-on-one. You can take it to the couch. You can take it to the coffee shop. You can take it on the road. You can put it on a desk, plug in a large monitor, keyboard and mouse if you need to.
Consumers expect mobility these days. Or at least, easy to move around and can run for hours on the battery. Desktop systems don't do either of these.
Consumer desktops are dead at this point. Even at work, we stopped getting desktop boxes 15 years ago. Everyone gets a laptop, a mouse/keyboard and two 24" monitors for the office.
Because you can take the laptop home and work.