Discussed at https://news.ycombinator.com/item?id=8302451.
A nice feature would be if there was a way to note which article links I clicked on or which comment threads I have visited. (If I comment then it's easy to find but I read more than I comment). That way I could just browse back that history and could have easily found that article that I was looking for.
I suppose we could save/serve which comment threads users have visited but that would be a lot of data, so I wonder if it wouldn't just replace one needle-in-haystack problem with another.