Valve is just focusing on Ubuntu and it's derivitives at the moment.

You can slide by with Debian based, but keep in mind that Arch linux is spesifically made to be lightweight, therefore lacks many libraries that would normally be deemed necessary for other distributions. The way it was explained to me, it seams like Arch linux creators and users don't like any file on their system that isn't 100% necessary. Including the libraries necessary would be a hastle, since they would need to worry about ALL operating system libraries which is something they probably don't want to do, and I don't blame them for. Especially since maybe not all of the libraries licenses allow them to be redistributed in such a way.

Indeed, we do not like having unnecessary libraries, but they do become necessary if we want to play these games.
I understand your point but I don't think including the libraries is a hassle on Valve's part: devs know what libraries their games need, they could either ship them with their games or provide Valve with a list, then Steam would need a wrapper for each distro's package manager to check whether the lib is installed (I believe this is done on ubuntu right now). The first would be easier on Valve and would facilitate debugging as every distro would be using the same libs, also eliminates the risk of a lib not being compatible with the game after a system update. The second would require a bit more work on Valve's part and make debugging harder but allow for a complete control over the libraries on the user part, however system updates could break the games.
Since we're talking about a game, I would expect it to work out of the box, indeed it conflicts with the shared libs philosophy which makes Linux what it is, and users probably don't want to have a hundred copies of the same library like they do on Windows, but it seems the most reasonable and easiest way to deal with the missing libs.

There are some interesting comments related to this in #94

Indeed, especially Tele42's, thx for the link!