Will a recommendation letter such as that written for John F. Nash be convincing?
Even though the event that inspired this questions may or may not have actually happened, the question is still a valid one. 

I suspect it greatly depends on who wrote the recommendation. If the person writing that recommendation is a great authority in this field and is known for not giving praise easily, then such a recommendation letter might help. On the other hand, if I were to write such a letter...