His point was trying to bet against a momentum trade or some other scenario was foolish. He watched time and again. There were opportunities to get with the crowd, or be on the wrong side.
A friend who works in quant finance said something along the lines of "if a trader can identify a mom-and-pop investor, it's like taking candy from a baby" in terms of making an easy profit.
Sure HFT guys are faster than you to get short term signals and make money on the micro scale - but even ignoring that way too many people are thinking they're beating the market and they really really aren't.
But that's a great point that any kind of active trading strategy needs to be compared against the right index. I think this holds true for pension/sovereign funds which invest in multiple hedge funds as well - comparing to the overall market performance may be less relevant than comparing to sector-weighted market performance, for example.