You must be young. There was a time when Closure was the most used library for minification. Before that it was the YUI Compressor. Anyways, Node came out and U

You must be young. There was a time when Closure was the most used library for minification. Before that it was the YUI Compressor. Anyways, Node came out and Uglify worked with Node and Closure didn't and even though Closure had some benefits like dead code elimination (which was eventually added to Uglify but not sure if as good or not - regardless it wasn't there at first) Uglify still won out.