HOWEVER... applications are free to bundle key libs with their application. AS long as the ogl interface doesn't change OR libc doesn't then its just a case of finding the correct libs.
Thankfully *NIX has a SANE method of library management and as such multiple version of the same lib can live side by side ALSO thanks to the LD_LIBRARY_PATH variable applications can have local version of libs in their install directory
UT2k4 ships with a libSDL and an openal in its System folder
etqw ships with a libgcc, libjpeg, libSDL, libstdc++, libCgx86
HoN ships with a libcurl,libfreetype, libpng14, libspeex, libfmodex, libgcc, libspeexdsp, libstdc++
ALL to maximise compatibility (via controlling a certain version and build of some libs the app needs) across many distro AND as the distributions adapt.
UT2004 was released in... 2004 and still runs great on my Gentoo system. There are applications that were released around 2004 that will not run in Vista or Win7 and yet it is linux and its dynamic system that gets slated... seems to be more compatible and stable then windows could EVER hope to be
To make out that in Linux having an application wouldn't be simple isn't taking into account everything that linux provides for flexibility.