What
The alternative to that, before the rise and acceptance of index investing, was people using their 401k money to buy individual stocks. But we all know that your standard mom and pop investor is not going to have time to cut through the bullshit and effectively research companies when they have a 40hr/wk job, a family, hobbies, etc. So those 401k investments were based mostly on personal hunches, word of mouth, and pump and dump schemes. That was really dumb money, and did even less for the economy.
So while I agree with you that index investing isn't doing a ton to push corporate management to do better in the way "smart money" does (in theory), when you consider the world before index investing was a thing you have to admit that money today is on average "smarter."
Average people should be able to grow their wealth over time without throwing money into inefficient instruments.
By analogy, house flippers rely on a market for turnkey homes.
My point is not so much to decry index investing as evil as to point out the irony of index investors complaining about more productive forms of market participation.
For all the faults in the industry, fundamentally, private equity provides a means to invest in private companies that can benefit from loans or funding rounds, while also offering a return on investment to smart private equity investors. There have been plenty of scandals with private equity firms taking advantage of bankruptcy laws in large companies, but the industry as a whole seeds companies of every size, even though you only hear about VC firms in the tech startup bubble.