Why do celebrities feel the need to spout off on medical or scientific matters?

FORBES: Stars Vs. Science

The blog mob loves to spout off about First Amendment freedom, except when it seeks to deprive foes of the same.

FORBES: Magazine Article

But by letting his guests spout off unchallenged, leaving the impression they were telling the truth, he has occasionally caused lasting damage.

FORBES

So, really, what is the point of all of this besides allowing a bunch of talking heads to spout off and generating headlines around the world?

WSJ: New York City Soda Restrictions: Ounces of Outrage