Installing on linux is as hard as the devs want it to be, if they make a package and give it to the repositories distributions of linux use people can get it easily through software centers, apt-get command synaptic etc, they don't have to make files you have to compile into debs and install.
Linux is very user friendly now alot more so than it used to be, also the people who want to play the game on linux probably know how to install things properly anyway.