There is no reason why fractional reserve banking could not be done with bitcoins. After all, it existed when the U.S. was on the Gold Standard.
It can't be done with bitcoin, because you cannot produce more bitcoins like you can dollar bills...And when the banks have to fufill the loan, they will have to send actual bitcoins to fund the loan....
The reason it was done with gold was because instead ofsending people actual bars of gold, they were sending them a bond that stated that they owned this much gold in return but were overselling the bonds compared to what they had in reserves....