It is one of those ideas that sounds good but people won't use it - I have no objection to people with false accounts as long as they don't try to gain from it fraudently financially, friendship wise or relationship wise. The people here who get annoyed by catfishes usually find them out quickly enough with reverse image. Really it is just common sense that if some dynamic develops to swap pics for proof and if any doubts still feature ask for a specific pose or holding username.
If it actually works to reduce the amount of catfish then I don't see why not try implementing such a feature? As long as there is enough credible evidence to prove that the user is indeed a catfish before kicking them out permanently and banning them from GAG forever.