Seems like Valve is spot-on with that X%, and maybe even lowers it a little by offering such a great service and caring about their customers. That sounded fanboy-ish, but it's the truth.
If it isn't on GoG or Steam (or Humble Bundle) I just don't buy it. I don't have that much time for games and will just go without. Steam is an amazing service, I am surprised that movies and music have not followed suit.
While I have a number of complaints about the Steam client, the service itself is fantastic.