I have wondered about this myself. About how to use the word scarf or scarves. Does one mean a type of scarf? Or do you say scarves when you’re talking about more than one piece, and scarf when you are just talking about one.
I guess neither are right. The original and most used was scarfs before the 20th century. After that, it lost popularity and people started using the word scarves. One reason could be because the word scarfs can be used to say ” he scarfs his food down”.
So when talking about the pretty material we use to add a bit of class, flair to an outfit we would use the most popular word Scarves.