They fought the compiler wars with real engineering, giving Borland a run for the money. Different people have different opinions about Visual Studio. As a Linux user since 0.9 I did not like its architecture and focus on GUI at the expense of everything else, but I still saw it as a consistent framework done by excellent engineers. And so on.
That said, I doubt the average person on a laptop even needs a general computing device, so your point does make sense. Though, is carrying around a screen and a keyboard and cable any better than carrying a laptop?
I could see an argument of it being cheaper, but that would take years, possibly decades, of multiple competitors in the space for the market to make that true.
Now, if we could have a decent folding keyboard and monitor that fit into the same case as your phone, that would be a game changer, but I don't think anyone is risking the investment to develop that.
We have laptops because it makes sense. Look at Apple's Macbook Neo. The tiny logic board on that computer is the least of Apple's worries. The most expensive components are the display and case. Why not charge 100 bucks more and not have to worry about this thing being a phone accessory?
The only way it would make sense to use your phone is if the keyboard and monitor can fold up so small that they can attach to the phone and still fit in your pocket. Otherwise, just using a laptop is going to be better every time.