This just isn't true. You could argue that Dallas can't afford to make blunder this big...and this was a big one, but to say successful organizations don't make mistakes this big just isn't true.
Just a few examples
New England Patriots: Drafted Chad Jackson in the first round in 2006. Played in 12 games as a rookie, 2 as a sophomore and was released after his third training camp.
Philadelphia Eagles: Drafted Danny Watkins in the first round in 2011. Played in 12 games as a rookie, 11 as a sophomore and was released after his third training camp.
I could probably keep going, but these two jumped out