We are only talking about it because people's "vibes" are that GPT-4o is "the best."
If a contrary result were found, the social media public would gravitate to something else written in the aesthetics of a primitive Gradio interface with some academic affiliation that told them the story they wanted to believe.
It doesn't really make sense, one way or another, than totally different models should perform so similarly, or even so differently, from the specific LMSys ranking task of "edify the end user." There's no explanation or analysis for the result. But because we "feel" "like" Anthropic's "big model" and Google's "big model" should perform the same as "OpenAI's big model," but because we also feel that "OpenAI is the best so it's latest model is also should be the best," well the results could say anything in any benchmarking approach, but we talk about LMSys's because they agree with our feelings, and we don't talk about other results because they do not.
If someone had a good way to benchmark LLMs, they would instead author training data.