I think Haskell underestimates people's intelligence when it comes to things like mind-simulating state change in simple subroutines, and overestimates it when it comes to understanding lazy evaluation and monads. Humans had built useful structures long before they've been capable of rigorous abstract thought. How? By trial and error. Most people find it easier to learn how to catch a ball by practicing rather than by calculating its trajectory. I'm not saying that is always the right approach, but it does come more naturally to the human brain.

Haskell discounts the very useful choice of reasoning about your code after it runs, favoring, instead, all-upfront reasoning, often at the expense of facilitating the former. There are some domains where figuring everything up front is very important. Others, where trial and error is far more productive.

Trying unfamiliar things is very good advice, but not for an important project you want done relatively quickly, and which you'd have to maintain for years to come.