My view is that this may be true in isolated circumstances, but you need to be very careful of the origin of this advice. In the last decade, as money has poure

My view is that this may be true in isolated circumstances, but you need to be very careful of the origin of this advice. In the last decade, as money has poured out of actively-managed funds and into indexes, people who make their living from management fees have gotten really worried and have sponsored a lot of submarine stories spreading misinformation or outright falsehoods about index funds. (The Wall Street Journal has been a frequent source of this stuff). Most times when I see an article skeptical of index funds it either quotes, or in some cases was literally written by, somebody managing an active fund which has seen big outflow recently- thus hitting them in the wallet. It makes it hard to take seriously that they're offering unbiased advice.