The ‘desktop’ in computer lingo refers to two separate ideas: the fact that a desktop computer isn’t portable (it sits on your desktop) and visual metaphor of the interface (the opening screen with your files sitting on it is your metaphorical desktop.)
The laptop computer doesn’t have the same relationship – sure, you can use it on your lap – but it still uses the desktop metaphor for the computer interface. You can’t lay out all your real-life files on your lap as you can on your desk.
In this respect, I think the move away from multitasking on the iPad represents a genuine ‘laptop’ computer. Singular focus, relaxed usage, in line with how you would actually work when you’re on the couch.