S&P500 had a rule from 2017 to 2023 that prevented companies with dual classes of shares (the sort that allow them to maintain founder control- like what GOOG and META did) that went public after the rule was instituted from ever being in the index. To be clear, META and GOOG were both in the index, but it was to prevent new companies from coming along and doing it. (I think it was related to SNAP going public?)

They removed it largely because investors wanted higher returns, and the tech companies that had such dual classes (1) were doing really well, and the S&P ended up caving on that rule.

1: Perennial hot button around here Palantir did this in a more extreme fashion than most. The three founders F class shares will always be at 49.9999% of the votes and the early investors B class shares have 10 votes each as compared to the publicly traded A class shares 1 votes.