If you are, say, in FSKAX at Fidelity, and suddenly "OAI" lists for a gazillion dollars, you might suddenly be quite overweight in a stock that you don't care for. Nvidia and the rest are already warping such funds.
"An index fund, by its nature, must occasionally dump stock I like and buy stock I don't like simply because the entire stock market dumped the stock I like and bought the stock I don't like."
and of course, hype is extremely valuable returns wise, and institutions play into that as well
I have given up trying to evaluate the market from sane fundamentals while grifters make money from pumping and dumping meme stocks.
Quoted for horrific wrongness.