"Linux is not ready for Steam", first of ... what is the linux actually ready for in first place, it has the constantly developing things of from the things of kernel to software without really any stops around.
When we would talk around thing like Steam, we would talk a common thing in way of like Gnome desktop, it shows desktop that we can use things like browsers for internet, game on etc.
Steam would run on top of that and on around constant rush towards from those of developers from each side on.
Yes the Steam could run on minor issues on between gtk/qt sides and on around trying to please most of the persons while some minor thing would gone un-noticed, still being we are not really thinking on the "final" build things on like on the Windows side where one thing is set and on around fixes send to the current thing as if found but rather more features added to make the build more than it was previously that could eventually come as issue from the softwares that supported the older behaviour.
What is the final build for Linux/Gnu softwares eventually at end, user space of desktop and standart APIs of what folks could use to enrich the look and feeling of while on around some folks argue at around things like can or cannot Steam run on Linux we could read more of in articles around the internet can oss/alsa and wrappers pulse work on really.
(If you can run a web browser and random software that would work on it's behaviour do not whine too much, at some point hopefully they would come in agreement of software freeze points on from where no new features would be added but rather random bug fixes only for year or few like on some other software companies behaviour, what would eventually mean bit more stability towards the end users instead of throwing random new things on like currently.)