Are you kidding me? Are you honestly denying there's no connection between the stuffing of the order book with hundreds of thousands of orders and the crash? Please. As for whether it's deliberate - I think you're right in the sense that something acted in a way which its creators did not intend if you think quote stuffing is a legitimate trading strategy we're clearly poles apart in what purpose we believe markets are meant to serve. I hear a lot of about how HFT creates liquidity and reduces volatility without much reference to quite what time periods they're talking about, what you don't hear them say is what it does to liquidity volatility, particularly in nervous markets and around announcements. I've done HFT too, I understand the game, the difference is I realise it's at best an illegitimate quirk of technology and at worst legalised front-running and the turning of the execution environment into a trading weapon.