> accurately reflect the market. When S&P rules end up excluding a significant part of the market with trillions

Define what that means? The weights are based on the value of shares available publicly, not market cap. So even if included SpaceX wouldn't even be in the top 20 and have a lower weight than Johson & Johson.

A lot of what people are saying here seems to be based on a misconception of what S&P 500 is supposed to be. Maybe it became the most popular index because of those rigid rules?