Other than the Goldman Sachs conflict of interest bit, I thought it was a pretty fair article. There's really no question that Index Funds are the best option for the individual seeing FIRE.
The problem is, markets are supposed to reward winners and thereby encourage growth, but Index Funds by definition don't do this. The big companies are going to have highly valued stock just because they're big companies.
When only a small percentage of the market operates that way, the distortion might be minimal, but Index Funds are so new, that we really have no clue how the market will act if 80% of the market is owned by Index Funds.
(Side note: There are many, MANY other Wall Street funds and practices that distort the market, and Index Funds happen to be one that helps the little guy invest without being killed by fees. So Goldman Sachs can go f*** off with their faux outrage)