It's on purpose to discourage that type of submissions. The links in the text are not converted to real links. And also, these submissions have a penalty so it's more difficult for them to reach the front page. If possible, I recommend using a normal submission.<p>Anyway, if you want an official reply from the mods, try writing an email to hn@ycombinator.com
You gain flexibility by letting your browser handle such things. Have a look at Stylus <a href="https://github.com/openstyles/stylus" rel="nofollow">https://github.com/openstyles/stylus</a>, which is a privacy-conscious fork of Stylish for Chrome, also compatible with Firefox as a WebExtension.