In my opinion it's because Haskell sits at the intersection of a lot of high power-to-weight-ratio features that let you build very robust and expressive pieces

In my opinion it's because Haskell sits at the intersection of a lot of high power-to-weight-ratio features that let you build very robust and expressive pieces of functionality at any abstraction level. That means that libraries can easily build on each other. A lot of cool gadgets in Haskell would have to be built into Python at the language level to be usable (note the proliferation of keywords in Python..).