This is somewhat addressed in the article. One of the criticisms is that index founds don't do enough, resulting in more power to the CEO and less oversight. Giving voting power to individual owners would reduce engagement even further, giving even more power to the CEO. There might be some ways to improve this (let investors transfer voting power to e.g. non-profit organisation who vote for them) it's unclear if this would not simply shift the problem
However, this becomes a bigger issue as index funds gain additional scale. As shares owned by index funds further surpasses the number of shares demanded for borrowing, index funds will be left with more shares to vote.
This will likely reduce shorting costs and increase total shares sold short somewhat, but likely not enough to compensate for the additional index fund ownership (i.e., index funds will net still have more shares for voting).
The average index fund owner is also not likely be spending time looking over the voting possibilities of 500 companies and aligning votes to decrease competition between them, even if that was possible. They just wouldn't vote on issues. The problem is that three funds can decided to vote on policies that reduce competition between companies and that they are big enough for the votes to matter.
Transferring votes to the underlying owners of the fund would in reality likely just cause those votes not to be cast. It is similar to just saying that the funds can't vote, but doesn't disenfranchise people who really want to vote and still gives all those shares the index funds own possible power.
We're all worried about companies doing things to compete that are not in the interest of society, right? Less competition equals less (fewer?) externalities. Why even have companies in the first place if competition is simply always a good thing? Why was Eddie Lampert's clashing departments at Sears (supposedly) a disaster?
www.yourstake.org
How do you get the fund to vote on the investors behalf ?
Things may have changed
Something like create a super-voting share class for active investors and regular stock for the index funds?
They don't preserve the right incentive structure and remove escape valves the regular stock holders should enjoy. I thought the original idea here is to let the index investors direct the fund how to vote with their portion of the index's stock. A pretty neat idea that de-fangs much of the incentive risk if the index fund management goes rogue or an activist investor tries something.