Ask PG: Why not allow links from the text field on submissions

I frequently see ask HN articles that are posted with links in their text field. I have read the submission form where it says "If there is a url, the text will be ignored" but I don't understand why HN does that. HN is my conduit to interesting articles and links are the fastest way to get to these articles when a little context is required.

My question: Can you make those urls into hyperlinks? If not, why?