You might also google stories about market makers not answering their phones during times of high volatility. There is this strange obsession over "how it used to be", as if it was better having people in the mix matching orders and providing that liquidity. The fact of the matter is, those people were as deeply flawed as any algorithm. The major difference today is that there is significant competition to provide liquidity in US equities markets and that liquidity can be extracted ON DEMAND by any trader.

Did you know, in the past it was NOT POSSIBLE for you to post a limit order and have it displayed in the order book unless you were an anointed market maker on an exchange?

[edit: this was meant as a reply to gdl not tptacek]