Notice how the article doesn't even give an example of a so called 'lazy stock' or even a sector. Vagueness is usually a sign of BS. I recommend the 'buy stocks that go up' method. I picked AAPL at 55, GOOG 413, Chap 35, and many other winners using this.
Active traders keep the markets efficient by using new information to agree on the best price. Index investing is parisitical because it feeds off the decisions of others. At some threshold, over-indexing will lead to diminishing returns.