> The idea that this composability is unique to Haskell is false. Java's streams are an example of exactly the same thing in another, non-functional, language. The Gang of Four "decorator", "composite", and "chain of responsibility" patterns are further general examples.

Certainly the concept of composability isn't unique to the Haskell community, no one's implying that it is. In fact, part of the point is that even these specific abstractions aren't unique to Haskell, but available anywhere, as they've been borrowed from mathematics. Composability and consistency are things that the mathematics community does exceedingly well, and the Haskell community has chosen to learn from them, while most other language communities do these things poorly, as they've chosen to reinvent the wheel. The GoF Design Patterns, in particular, are a rather verbose reinventing-the-wheel of well-known concepts like partial application, but with inconsistent vocabulary and implemented with regards to the limitations of some specific language's semantics, and do a poor job isolating the minimal set of constraints necessary to get the intended emergent properties. Calling a person or community arrogant for trying to highlight the utility of learning these lessons isn't helpful to anyone.