These sections seem to address the point to me:
* "The tail is not wagging the dog" - index funds are a relatively small percentage of total share ownership.
* "Benchmark huggers have always been around" - owning ~the index was not started with index funds.
* "Active funds literally own the market" - the sum of portfolios of non-index funds ends up having the same profile.
* "Price discovery is a cop-out" - relatively small part of the trading volume.
* "Liquidity is not a huge problem for index funds" -no market impact to sell (v dubious if you ask me), unlevered.
* "Humans matter more than fund structures" - the absence of index funds did not prevent bubbles/crashes.
You can disagree with those points (I do with some of them) but that's a large part of the article.