Because they classify it as blog spam, despite explicitly requesting it if you have your own comment to make.
> If you want to add initial commentary on the link, write a blog post about it and submit that instead.
> If you want to add initial commentary on the link, write a blog post about it and submit that instead.
EDIT: Nevermind, I found it in this paragraph:
Don't abuse the text field in the submission form to add commentary to links. The text field is for starting discussions. If you're submitting a link, put it in the url field. If you want to add initial commentary on the link, write a blog post about it and submit that instead.
Notice, people below were talking about RapGenius specifically, their VC, and how much a license costs - yet that stopped once the editors modified the URL & headline.