I have only done Haskell during college and my friend is doing Haskell in web backend in production so I'd say I have a pretty good feeling about the skill gap in Haskell. There are many concepts that he tries to explain to me which I don't get 100% but it really does feel like all I need is more time. It was like that at first with monads and then phantom types, row types, hkt etc. I'd say the biggest detractor for people is that it takes more than 1 blog post and 1 hobby project to comprehend everything. It may take 1-2 years to learn all the concepts. To me the beautiful thing is that the concepts learned aren't some language quirks but instead general programming/math concepts which you simply cannot think about in simpler languages like C#. With all that, I'm still heavily put off from Haskell by all the tooling and I just can't let go of the comfort of working in Visual Studio. In 10 years I hope either C# gets some of my favorite things from Haskell like HKT and better inferrence or Haskell gets better tooling and broader ecosystem. My bet is on the former but gafter keeps postponing HKTs spec after spec.