Well, I can always adjust the number of posts per level, or add more. I'm not expecting to attach a lot of meaning to 'em.
I don't see the big deal about rising in the ranks either, but unfortunately some people do. The biggest problem, I've found, is people making loads of nuisance posts -- one liners, smiley only, or nattering on about things that add nothing to the topic being discussed -- to see the title change under their name.
I assume that the existence of the "report to moderator" link implies that it's possible to remove nuisance posts, in which case the question would become: does your total get decremented if one of your posts gets nuked?
Course it does. In any noninsane forum system, it keeps track of your posts in real time. For instance, over at OverClocked Remix, a handful of months ago they removed all the threads with over a few thousand posts, to save on disk space. Some people (mostly postwhores) lost upwards of a thousand posts each.
Off topic: Actually, it depends on the board software. Some keep track of each post, so something like your example would affect post count, but some just add 1 to the count of posts each time a post is made, so it doesn't matter if an old post is deleted or not.
IE, for the math inclined, there are two ways to keep track of post counts:
post count = sum(posts)
(which adds up all the posts in the database at a given time, and can be affected by post deletions)
vs.
post count = last_post_count + 1
(which adds 1 to the count each time you make a new post, and is not affected by post deletions because it is not counting all the posts in the database, but is instead adding the number "1" to the old post count number each time you make a new post).
