i think exchanges are just as bad or even worst than banks.
1st they both rip you off..exchanges more so. (look at at % they charge for selling/buying or even moving funds out..(imagine what they would do if they had the power and means to loan money using smart contracts for example.
2nd exchanges get "hacked" and you lose all your money.
3rd sometimes they just refuse to give your coins back by pretending theres some sort of glitch and by not answering "support" emails etc
4th exchanges are that 3rd party that bitcoin was created to do away with in the first place...so the purpose is defeated.