Because the internet is filled with stupid comments
The solution we're creating is simple: an open-source filter software that can detect rampant stupidity in written English. … The primary challenge inherent in our task is that stupidity is not a binary distinction, but rather a matter of degree. To this end, we're collecting a ranked corpus of stupid text, gleaned from user comments on public websites and ranked on a five-point scale.
YouTube comments = ranked corpus of stupid text