The whole command-line tools in JS trend was, I think, in full swing in 2013. I mean even in the 2013 version that another commenter linked, they're relying on the built-in NPM support for installing command-line tools and the existing popular NPM packages for command-line parsing and output.
And if people were trying to fight that trend (which to be fair is a bad trend; I refuse to run software from the NPM ecosystem to this day), this is a weird example to pick because the point of the tool is to use JavaScript's regular expression syntax.
I think there’s still some hate towards JS now, and in 2013 it definitely was much more rampant.
Also funny to think that this project probably received so much hate because of being ahead of its time.