The conventional wisdom around here is that you can't beat the market, it's efficient, all information is already incorporated, you should buy index funds, etc.

This is good advice for the vast majority of people. It's possible to beat the market, but you're unlikely to do so unless you're backed by significant capital and it's what you do for a living (see: Rennaisance, Two Sigma, Citadel, etc).

Ask yourself this: if you had the hottest of hot stock knowledge (and could legally trade on it), what would you do? Keep quiet and buy the stock yourself before word gets out, or sell the advice to a newsletter audience?