Of course it's about function application. All of programming is about transforming data. This is obvious. Some procedure must be applied to some data to transform it. There is no programming paradigm or language that avoids this and therefore it is not worth discussing.
I bring up composition because this it is the most important differentiator between FP and all paradigms. I wrote about it another reply:
I bring up composition because this it is the most important differentiator between FP and all paradigms. I wrote about it another reply:
https://news.ycombinator.com/item?id=22292105