I don't really have an issue with any particular point made in the referenced article. The three 'truths' articulated are pretty helpful: short term timing is very difficult, ride your winners, and sell you losers. If you are a professional trader, I'm sure you'll find these bits of advice helpful.
The problem I have with articles like these is the overall notion that people at home can somehow hope to beat the market. Yes, you may know someone who bought Citi (C) in 1990, and sold in 2006. And, maybe you know someone who got short Toll Brothers (TOL) in 2005. These are the exceptions and are not examples you can reasonably expect to follow. It's like buying a lotery ticket becuase your nextdoor neighbor bought a winning ticket the day before. The fact is, the odds are stacked against you.
Beyond the allure of getting something for nothing and/or straight gambling, I think most people dont understand the enormouse disparity - in the amount, quality and timing - of information between someone at a desk in a major shop and someone at home watching CNBC. Throw in the cost of capital, the benefits of volume, and client relationships... you really don't stand a chance.
As individuals, non-profesionals should focus on asset allocation, and matching assets to futur/potential liabilities.
If you're the genious who's been beating the market for 10 years while sitting at your beach house, congradulations. I don't think it's fair to use your highly unusual success to propogate the fantasy of getting rich trying to pick stocks.
Disclosure: I have very small positions in both C and TOL as I do like to gamble every so often.