Also here is a Linux joke for you:
If you don't like certain things, just fork it and do your own thing.
Dual monitors should be plug & play. I shouldn't have to add a new repository to apt-get, I shouldn't have to choose between 15 Nouveau drivers and 15 potentially system-breaking nvidia drivers. It should "just work".
Dual monitors, and just display output in general... this is 2017, this is very basic, expected functionality. It doesn't matter how complicated it is to implement - the user doesn't give a shit, they just want two monitors.
Evidently it does matter how complicated it is to implement, or it would just work by now.