Composition in this sense is talking specifically about composition of objects. By definition, that's only going to be possible in languages with objects. No other paradigm achieves that (for better or worse).
From what I understand, composition in OO basically means that I put another object as a field in my new object. Is that correct? If so, I don't really see the fundamental difference from doing the same thing with a struct/record: put another struct/record inside another struct. Especially if I can use encapsulation to hide the internal structure of the struct/record.
