I'm wrong. I just tried it; although something led me to believe that it still counted.
perhaps some ppl have just schmooze post counts grandfathered in? It also depends on how the stats are stored, if they are in a sql database perhaps once there are too many posts from the user there is too much stress from calls to the database because the tables have too many lines so it gives back an incorrect number. That is why a new member like myself has the correct ammount because it dosnt need to dig into 5 years of info to gather my post count.
If this is the case I would suggest to the admin to put the site onto maintenance mode for an hour or so and do a complete audit and get fresh numbers and then cache them. I would not be surprised to see major drops in the post counts. For all we know there could be corrupt portions of the db which are giving a false reading my having duplicate entries.. This is common when forums keep upgrading.
Just my 2 cents (from Google wallet?)