I dunno, but it is included in many commercial libraries (free ones tend to be less reliant on large dependencies); a lot of people know it and a lot of people don't even know how to start bundling a node (or dino? what are people using now?) project; and it has a lot of extensions that really impress some people.

Besides it having a way more convenient API than bare JS. (That honestly, I only don't use because bare JS is conveniently documented by MDN, otherwise I think I'd be fully on it too.)