Literally the index. If you track the NASDAQ as part of your index you must obey it's inclusion rules.
Contrary to (apparently) popular opinion, index funds are not people.
So, who is being forced to buy that index?
A lot of employer pensions will have limited fund options. (At least in the UK, maybe the US works differently.)
Quite likely that the only sensible one for most people (~global equities) will track S&P 500 internally. So essentially employees are being forced to hold whatever the index includes.
Hopefully it's less of a problem with Nasdaq, but it was a real worry.
Turns out people (and institutions like municipalities and pension funds) sometimes buy index funds before SpaceX enters the NASDAQ 100, and changing their policies over a single event would be a great effort and expense, and set a bad precedent. Sounds crazy, but it's true.
Nobody has any idea what point you're trying to make, and the fact that you're repeating yourself and not being clearer makes everyone suspect that you don't have any idea either.
Ok but there are very few indices following NASDAQ, compared to S&P 500.
It's not NASDAQ as a whole... it's NASDAQ 100.
https://etfdb.com/index/nasdaq-100-index/ are the ETFs that track that index.
Yes sorry I meant NASDAQ 100.