Shouldn't being involved in an interesting project (e.g. Steam Client) mean you'd actually want to see it through to completion and iron out bugs, etc. - assuming the developers actually care about their work?
In practice, makers are different people from polishers, and Valve's system of hiring the "best" (people with impressive CVs) and salaries based on stack ranking means there is a huge bias towards makers (Who brought the company more money? the person who helped roll out dota2 or the person who fixed edge cases in the steam client?).
Many of Valve's products are full of bugs that don't get fixed for years. And since they only hire the "best", they don't have any testers. Many times patches are released that cause servers to crash within seconds (tf2 falling damage crash). And sometimes they release them on Friday which means it doesn't get fixed until Monday (Overflow error writing string table baseline crash). These patches were also mandatory.
Edit: though, to contradict myself, this is still as gameable as all hell if you do something silly like connecting it to reward and punishment.