I'm not sure I'd agree RMS is always right...but I'd bet he is probably right about this (I'm sure you didn't mean that exactly though!).
There is a lot of unnecessary dependence here with valve. GNU/Linux in general though has a lot of that really. It works though because it ultimately comes together.
Even if/when one distribution disappears the software is available. Not so much with valve. It'll only work so long as valve is into the GNU/Linux market.
