They aren't making the market less efficient, because index funds create value for many people for the reasons you described. The market inefficiency is easily

They aren't making the market less efficient, because index funds create value for many people for the reasons you described. The market inefficiency is easily corrected by day traders and market makers. I'm just saying that index funds do not make markets and economies more efficient, as the article claims, so if we had a 99% ownership tied up in index funds scenario, markets would indeed be far less liquid and more volatile.