That's the thing, FP is not only a great model for writing a CRUD or any kind data-processing system, but also things like Haskell's type system makes it incredibly powerfull to "hack away" code while controlling complexity. And both are things that FP extremists doesn't seem to like to promote. The "scientific" culture seems to revolve around using it for numerical computations, while trying to get as close as doing "formal proofs" as possible.