Fractional Reserve Banking naturally exists, and unless it is outright banned (which would be a violation of freedom) it always will exist. Ironically, most debt is based off of banking, and without debt, you have huge currency volatility. Debt ensures future demand which actually stabilizes a currency.
The problem is with US FRACTIONAL RESERVE BANKING which is where money created with through the fractional reserve process is identical to "normal" money, due to a combination of the FDIC and the FED, especially when the FED gets its instructions from the government and from a coallition of big banks, guaranteeing it will lend to both almost infinitely.
We are ok with; one to one lending. We are NOT ok with:
1. Banks or exchanges like MT Gox that create off Blockchain coins. This is just FRB in crypto form.
2. Shadow banking type arrangements in its various forms.
If everything stays on the Blockchain, FRB will effectively be eliminated.
FRB is completely unavoidable given a somewhat stable currency.
1) Stable currency gives lending less risk, requiring a < 100% reserve requirement.
2) With < 100% reserve requirement, banks can pay interest to depositors while forcing investors to take minimal risk (maximum interest = their interest rate ( 1 - 1/reserve requirement)
3) Investors accept interest for minimal risk originally in the form of bonds/CDs.
4) Since there's minimal risk, bond/CD notes become as effective a store of value as normal money.
5) Merchants begin to accept bonds/CDs in lieu of "base currency" because there isn't any downside to doing so (they were going to buy bonds/CDs anyway because they have minimal risk and provide interest, and accepting bonds/CDs increases the supply of tender available with which to buy merchant's products, increasing demand for merchant's products, creating more sales == more profits).
And a fractional reserve system is born.
The answer to this is the Blockchain. On blockchain = money; off blockchain = not money.