> I feel like this rush to adopt functional language features in non-functional languages is
Very few languages in use are fairly described as "non-functional"; pretty much any structured programming languages that supports function pointers supports the functional paradigm. A language doesn't have to be pure to support functional programming.
Without closures, or something that well approximates them, it seems hard to say a language "supports the functional paradigm". You can write functional code in C, but beyond very simple things you're implementing most of the machinery yourself.
"A language doesn't have to be pure to support functional programming."
Very few languages in use are fairly described as "non-functional"; pretty much any structured programming languages that supports function pointers supports the functional paradigm. A language doesn't have to be pure to support functional programming.