This would be especially useful on **mobile devices**, where:

   * Cutting and pasting the title of a question and then its URL is a huge pain, because it involves switching back and forth between the comment page and the page with the question to be linked, without the aid of windows or tabs.

   * Have you ever tried editing Markdown on a mobile device? Moving the cursor and selecting bracket characters is not fun. And better get it right the first time, because clicking the edit button afterwards is even harder.

   * Userscripts aren't available on mobile.

As for **Jeff's objections** why it *can't* be done:

   * "Comments are processed on the fly." Just look up the title once and add the Markdown that we would otherwise have to type manually.

   * "If you want this, put your links in a post, where it is already supported." Huh? 95% of the time I post a link to a comment, it's on *someone else's post*.