alt Hacker News> everyday business and physics is monadic in function.
So?
> And if-then statements are functorial.
So?
All the "this is hard" stuff around these ideas seems to focus on managing to explain what these things are but I found that to progress at the speed of reading (so, about as easy as anything can be) once it occurred to me to find explanations that used examples in languages I was familiar with, instead of Haskell or Haskell-inspired pseudocode.
What I came out the other side of this with was: OK, I see what these are (that's incredibly simple, it turns out) and I even see how these ideas would be useful in Haskell and some similar languages, because they solve problems with and help one communicate about problems particular to those languages. I do not see why it matters for... anything else, unless I were to go out of my way to find reasons to apply these ideas (and why would I do that? And no, I don't find "to make your code more purely-functional" a compelling reason, I'm entirely fine with code I touch only selectively, sometimes engaging with or in any of that sort of thing).
The "so?" is the part I found (and find) hard.
There is no 'so?' Haskell tends towards applicatives and monads because monads and applicatives are the preferences of haskellers. Just like JavaScript people may like dynamic typing, etc. These are design choices.
By modeling various things as monads, you get the various principled monad extensions. Unlike normal programming where leaky abstractions are the expectation, using algebraic structures with principled laws means things just work.
But this has nothing to do with monads in particular. Haskell's choice to do a lot with monoids provides a similar guarantee about things that combine . It's a preference. Nothing like monoids exist in other languages, because people are told they have to think with 'objects' of whatever.