I didn't mean to imply that Valve's contributions have not been significant in improving the situation with Wine, only that unlike the other examples Wine was already good before the involvement of a wealthy company.
Wine was a great technical achievement, but I remember it taking me hours crawling through WineDB and reading config guides to get most games working. Even for someone in the know, it was very impractical compared to clicking "Play" in Steam. That user experience makes all the difference.