You look at it the wrong way.The point is to make the system multi task.Its like you opening several tabs/windows. I often spend time browsing HN while my project builds in the background.Similary while a site I am opening opens(yes this is a thing because developers love making heavy websites these days),I shift to other tabs.

And when you have to port design specs to code.It is much easier to just turn your head instead of switching tabs/windows. This would indeed be a much better option.