For most of our history, when a SME (subject matter expert) heard CBS news say something he knew was 100% wrong or intentionally misleading, all he could do was write a letter to the station (ignored), yell out loud (waking up the kids, scaring the dog, and bothering the wife), or throw something at the TV ($$$).
Now days, he can go on-line, blog his specific knowledge of the issue, and watch while thousands either confirm, endorse, or add to his knowledge. Once you have a few thousand people validate your argument (and if you are wrong, you know REAL fast)then it gets picked up by an uberblogger and before he knows it; the shmuck that once just threw a pillow at Dan Rather's image on TV, has now caused CBS to be brought to its knees.
All this happens in the blink of an eye. Due to the joys of the internet, the MSM can no longer "get away with it." That is what torques them off. Like the French nobility in the late 1700s, their way of life is being brought down around them by peasants, and they don't know what to do but cluck-cluck to each other. Ain't life grand?!?