I was looking at it from a more institutionalized perspective I guess. At least in my field, I know how this works because I see it play out. People are conservative and sometimes would rather be wrong with the herd as long as it means they're not risking being wrong on their own.

Having said that I guess you have a valid point. Once major institutional investors decide an index has basically gone corrupted, then they won't actually buy the index fund anymore. They will just buy all the stocks in the index, and underweight the parts they think are tainted. That's what I would do, anyways.