I think that more traditional "profile-based" social media is well-suited to meeting new people. I have no interest in reading another person's "feed" of shared content and ramblings, but I am more inclined to perhaps read a short "About Me" if that makes sense.
Reddit emphasises them a bit more than HN, but still the natural reading flow is such that you miss the username. It's common for someone to comment, a second poster to reply asking a question, and a third poster to reply without people noticing he's different from the first poster.
Facebook emphasises the commenter more, showing their name in bolder text and a profile picture.
Some older forums (on phpBB, vBulletin, etc) emphasised it even more, devoting a large section to the left of each post to the commenter's name, statistics and often an avatar. These forums were much more prone to cults of personality than the likes of Reddit.
On the other end of the spectrum is 4chan, where posts are anonymous and content, or at least memes, is king. It doesn't seem like that necessarily leads to more nuanced discussion.