Earlier quoted context omitted.
That whole paragraph was bizarre. Yeah, lots of people are doing things wrong, but there is a competitive industry of index funds and ETFs out there. I'm sure they could be squeezed a little bit more, but not much.
I think this and the grandparent miss the point. The paragraph starts "it's too hard". Too much choice, lack of metrics, lack of clear comparisons can make things as hard as no choices. The availability of discount brokers doesn't solve the problem, as evidenced by the number of people making mistakes. "Most people either pick individual stocks and bonds and expose themselves to high volatility, or pay very high fees…
Telling people to just invest in an S&P500 ETF (metrics and comparison don't matter because people don't understand them anyway) doesn't seem like a great business, financial writers are already advocating it pretty regularly and investment in index ETFs is growing steadily.