It is true that there's a difference between an efficient market and a socially optimal market (if efficiencies are only measured in monetary terms, and exclude

It is true that there's a difference between an efficient market and a socially optimal market (if efficiencies are only measured in monetary terms, and exclude any accounting for non-monetary benefits and externalities). However rent control is quite a bad example. There is abundant evidence that rent controls produce serious under-supplies of housing, which is a socially negative outcome by any measure.