I wonder if Artificial Analysis could be influenced by certain model companies. Looking at the changelog [0], they updated a few times after new models appeared, so US models progression was much higher than that of other vendors (like when they updated the algorithm after Kimi K3 versus Opus 4.7, so Kimi dropped in the rankings). Or maybe thats just coincidence.
People still buy into "research" from Gartner and Forrester despite it being an open secret for decades that they are pay-to-play.
These kinds of "research" companies are there to validate people's preconceived ideas and purchasing decisions rather than being genuinely unbiased. And they are very useful for that, both for consumers and for marketers.
[0] https://artificialanalysis.ai/changelog