On the contrary. There are many benchmarks, some small subset of which are intended to reflect the whole market.

There are indices for every little thematic and niche corner or strategy or idea, there are broad-as-possible indices, and there are indices with requirements like listed age and profitability.

I'm not debating any of that. This discussion is about the S&P500 as a benchmark, which has an expressly stated purpose of tracking large-cap US equities.

This discussion is about if S&P500 actually achieves this benchmark, when it has (antiquated) rules that exclude large-cap US companies of the likes of SpaceX, Anthropic, and OpenAI.