This is likely because people don't have enough real-world experience with functional programming paradigm techniques like 'parse, don't validate' and modelling only the parts needed to handle dynamic input, e.g. as shown here https://lexi-lambda.github.io/blog/2020/01/19/no-dynamic-typ...

It's unfortunate that they decided to pick F# on such problems when they didn't have the (mental) toolkit to tackle them, but I think it speaks more to people being really eager to communicate their enthusiasm for FP. I wouldn't try to ascribe any higher meaning to it.