The problem isn't really that banks can create money. Ultimately it's up to the people whether they trust paper IOUs or not. The trust in IOUs happened organically and would happen again, unless you suggest they should be outlawed (ie. it's illegal to write a piece of paper saying "I promise to pay the bearer..." on it).

The problem is the governments can bail the banks out. After 2008, trust in paper IOUs (or their digital equivalent) should have plummeted, leading people to seek to store their wealth in other ways. But it didn't, because the governments stepped in and said, "nah, we need this to work, so we'll pay their salaries and bonuses with your taxes".

Bitcoin was intended to be a solution to this problem. There's nothing stopped people creating derivatives on top of Bitcoin and trading those. But nobody, no government nor anybody else, can just print more Bitcoin.