I find these kinds of terse shorthand features valuable: they allow for a richer experience for users who care enough about HN to make the effort to understand

I find these kinds of terse shorthand features valuable: they allow for a richer experience for users who care enough about HN to make the effort to understand the features that lie beyond the basic stuff, and for those who don't, they're basically invisible. I think perhaps something to consider would be a `title` attribute on a span surrounding the full stop which says something like "most recent comment by this user", so that someone who mouses over the dot can get more information about what it means (thus hopefully avoiding the Ask HN threads)