So thought experiment on this. Say 49.5% of the world buys pure index fund. 49.5% of the world what you said... and say, all avoided Pepsi stock. Wouldn't that mean that Pepsi stock is undervalued from a PE standpoint, and the 1% of investors left would go 100% in Pepsi, and make a crapload of money?
I totally get voting with your money. If you think some company is absurd for some reason, avoid buying their product. But to avoid buying stock? I think all you do is create an investment opportunity for someone savvy with numbers to make big money, and the company feels no different.
Please correct me if I am wrong though, I might be missing something in this argument.