A difference in the content of the two platforms doesn't mean that the comments on the two sites are so dissimilar that they can't be compared.

In particular, they remove the forum requirement of quoting the comment you're replying to, by allowing you to respond to someone's comment directly below it in the middle of an existing thread. It would be exactly as inconvenient to readers of old Reddit and HN threads if that context was deleted automatically 6 months after the fact, HN just doesn't let you do it.

> doesn't mean that the comments on the two sites are so dissimilar that they can't be compared.

Actually, it does. I discuss things of significance here, where the information may be useful to someone in the future, but I only commented on reddit for entertainment purposes (jokes, witty remarks, etc.) Also, creepy people don't comb through past HN comments looking to call you out in current conversations like they frequently do on reddit, and almost always out of context and spun to fit their agenda. While entertaining, it started getting annoying after a while, so in my opinion, that's why they can't have nice things, so to speak.