There is not a doubt in my mind that when flusha was exposed, Valve could have taken steps to prevent it from continuing. They chose not to - and to my mind that decision was taken in order to protect their profit.
So no, it's not at all ignorant to suggest Valve 'ruined the game'.
The very fact it has since expanded from blatant shitters like flusha - (who anyone with a history in the CS scene would tell you was suspected of cheating long before he ever joined fnatic), shows other players had simply had enough.
Who wants to practice for ten to twelve hours a day just to be cheated out of a victory by some scrub cunt?