Those Haskell threads are full of exaggerations. I don't know/use a lot of Haskell concepts and I can still produce software with it. You can be just fine with IO and passing everything as arguments. Which is, well, what article is talking about.
Every time someone has suggested I learn Haskell the discussion goes similar to suggesting I learn German. Sure German from a language perspective has some advantages over English in some situations. Some even argue that it's an objectively better language. But I live in Pennsylvania and speak English as a first language. Outside of moving to Germany/Switzerland/Austria, how do the advantages of German provide enough benefit for me to invest the massive amounts of time to become fluent?
Sure if we could turn back the clock on Computer Science education and have everyone learn lisp as their first language maybe we'd all be avid Haskellers these days and be better off for it. But given how history went it is "harder" to learn and less productive to work in due to external factors alone, regardless of how intrinsically easy/hard the language may be (which is entirely subjective).
I'd go as far as saying it's essential for anyone who likes programming beyond just a profession. Same with lisp.
You don't need to learn all of the language extensions or how to architect serious applications with free as the OP said but it's very useful knowledge and one of the pedestals from which all other languages should be judged.
Plus you'll understand why Idris and dependent types are an interesting future development in safety and language design. While also understanding the source and inspiration of many features in far more popular languages like JS and Rust. And there may be a real future in it via PureScript and other similar projects.
I think the major troubles for beginners with C++ is that you can't do anything out of the box like work with files, create a directory or perform a HTTP request. Whereas python or java are ready to use.
The closest thing i can think of in Python is passing a mutable object (like an empty list) as a default param value. C++ is littered with bug-prone landmines like that.