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."