It'd make sense to rename WebDev Arena to React/Tailwind Arena. Its system prompt requires [1] those technologies and the entire tool breaks when requesting vanilla JS or other frameworks. The second-order implications of models competing on this narrow definition of webdev are rather troublesome.
[1] https://blog.lmarena.ai/blog/2025/webdev-arena/#:~:text=PROM...
Who will write the useful training data without LLMs? I feel we are getting less and less new things. Changes will be smaller and incremental.