Why use HTTPS Everywhere when we have HSTS supported browsers?

Why use HTTPS Everywhere when we have HSTS supported browsers?

I know that the browser's default protocol to access any site is http:// when https:// is explicitly not mentioned, but even then if we browse to a website say www.facebook.com, the response header from the Facebook servers would have HSTS mentioned and our browser would direct us from http:// to https:// so why do we need another plugin to do this when browser itself does this for the user? What is the purpose of HTTPS Everywhere when our browser does it's job by default.