[MrJohz]

Is it? That seems like a very bold claim. MLs have been at the heart of a lot of language development for the last few decades, both as research languages for various concepts, but also practically: OCaml is fairly famous as a language to write programming languages in. FP isn't something wild and niche, it's discussed fairly regularly even amongst users of mainstream programming languages. Even Go has an FP library now, coming out of IBM of all places.

I don't think you can attribute this to ignorance, because it's very clear that Pike is not ignorant of programming language design - even if you disagree with his decisions, he has had tremendous success at implementing his vision. To me it speaks more of disinterest - FP doesn't seem to really register on his radar as a useful mine of PL ideas. That's fine, although I agree with the previous poster that it's ironic to be such a proponent if APL, and yet have such a blind spot to another very fascinating area of his field.