It's a mature library that takes the pain out of cross browser compatibility (yes... you read that right, cross browser compatibility is still a thing in 2019) and the verboseness of using native JS (yes... you read THAT right, using native JS is verbose), so why wouldn't you want to use it?
Oh and on more thing... If you're not using jQuery but instead using native JS with polyfills... YOU ARE A MORON AND DOING IT WRONG and should just you jQuery.
Oh and on more thing... If you're not using jQuery but instead using native JS with polyfills... YOU ARE A MORON AND DOING IT WRONG and should just you jQuery.