Wouldnt a fair counter argument be, that llms have been trained on way less fu ctional code though?

Like they are trained on a LOT of js code -> good at js Way less functional code -> worse performance?

You can write functional-style code in many languages, as I have in JS and occasionally Python to great benefit.

That's a very fair point. There are some publications showing lower performance for languages with less training data. I imagine it also applies to different paradigms. Most training code will be imperative and of lower quality.