EconoSpeak: The Infamous Example of Rent Control in Introductory Economics:

The latest post by Jodie Beggs rehashing the standard story about rent control has me quietly steaming.  It’s not her fault, of course: she is simply regurgitating what has become a mandatory morality tale, an unavoidable rite of passage in Econ 101.  You know the drill: in their misguided desire to be fair to the poor, the authorities have set a ceiling on rents below the market-clearing price, and the result is excess demand in the short run and reduced supply in the long run.  Now that you have mastered the supply and demand diagram, you are so much smarter than they are.

(Via econospeak.blogspot.com)

It is one of the problems with teaching micro in general. You get armchair economists, and policy-level economic analysis is usually a lot more complicated that the supply-demand stuff you are fed in “Ec 101” as the Haahhhhhhhvard people like to call it.