[tjoff]

Point was that there is a massive difference between 13" and 16".

You don't have to have it in your lap. But most people, in most cases, where the laptop screen is actually used for anything. Is much closer than you'd have a 32" screen. Especially if you are going to use the laptop keyboard.

Comparing preferred PPI between different types of devices is always pointless, because you don't use them in the same way or from the same distance.