Absolutely any exchange can create money out of thin air. Get over the ability to create money out of thin air and start focusing on the trust behind it. If I create $100 out of thin air but promise you to pay you $100 tomorrow and you are positive through a track record of me being paid $100 everyweek at the same time for 20 years that you will get that $100, isn't that enough to make the transaction? What more do you need in a functioning society?
If I lend you 100 bucks, and you promise to pay me 100 bucks tomorrow and memorialize that promise with a Matthew M. Wright note that's printed on fancy paper with your picture on it and maybe some hard-to-replicate holograms, have you really created "money"? Well, maybe. I could certainly try and find someone to trade for it and those pieces of paper might earn enough trust to be widely accepted as a medium of exchange. And maybe you could even start issuing more in Wright bucks than you've collected in U.S. dollars. That's not necessarily a problem assuming you don't go overboard to the point that people lose trust in your money. The problem with banks' ability to create money in our current system is that, due to implicit and explicit government guarantees (like FDIC insurance), there's no market check on the ability to create ever-increasing quantities of debt-money. If we had a truly free market for money, I believe commodity money (and I'm including Bitcoin in this category) would be the dominant form of money although there would still be some "monetary" use of debt instruments.
