Fractional reserve banking can be done with bitcoin just as with any underlying "base asset" such as gold or Federal Reserve Banknotes. It just means that the banks can lend most of the asset, and must keep back a fraction for liquidity purposes (in case a depositor wants some of their asset back).
In many ways Fractional Reserve Banking would be much more risky with bitcoin than with banknotes; with banknotes at least there is a lender-of-last-resort central bank. The central bank can create additional money at will to lend to a bank that is in a liquidity crisis, to see it through the crisis. With bitcoin, there is no such operator.
Now if nobody ever lends or borrows bitcoin, then there will be no issue - but lending and borrowing has been quite central to commerce over the last couple of centuries, with mostly decent effects. Personally I'm not sure bitcoin economics are that well thought out!
In many ways Fractional Reserve Banking would be much more risky with bitcoin than with banknotes; with banknotes at least there is a lender-of-last-resort central bank. The central bank can create additional money at will to lend to a bank that is in a liquidity crisis, to see it through the crisis. With bitcoin, there is no such operator.
Now if nobody ever lends or borrows bitcoin, then there will be no issue - but lending and borrowing has been quite central to commerce over the last couple of centuries, with mostly decent effects. Personally I'm not sure bitcoin economics are that well thought out!