It does to me because:
a) The first post is the one strongest tied to the thread as a whole in the database
b) It represents the thread as a whole better than the last post to the casual browser. i.e. if you open a thread and the first one is unread, you haven't read the thread, right?
c) If it's the last post there's no distinction between a new reply and a thread that's been unmarked read.
d) If it's the last post marked unread then it will require constantly updating every time a new reply is added.
|