I'm not saying that Haskell is as bad at imperative as assembly is at functional, just that being able to accomplish all tasks in a single-paradigm language does not constitute proof that the language is suitable for all tasks.

I love FP concepts, and I've enjoyed my experiments with Haskell. What I object to is that FP advocates don't push FP as a valuable addition to a larger toolbox, they push it as a single paradigm to rule them all. For daily work, I prefer a multi-paradigm language that allows me to choose a programming model that matches the domain well.

(FWIW, I have the same problem with OOP advocates who try to squeeze everything into a class. Some things are better modeled as pure functions.)