Ask HN: why no bookmarking on HN?

So I'm relatively new to HN. But it has become my number one information site. I love kicking back on my couch and absorb all these collective knowledge via my iPad (so no plugins option) what my experience is missing is an easy way to bookmark stuff. I know I can interact with a thread and use the "thread" link to see them, but that's not really a solution for me. I'm sure this is not a new topic. So how come such an obvious feature has never been implemented? Also I like to know if there are others who are interested.