Every time a viewer hits the "Latest Posts" button the page refresh's and you get to see the latest posts for all categories.
However, with the response "Server Busy" you can still click on the separate forum categories, one at a time and the page refresh's each time, and see the posts.
Result: Server available = 1 "click" is registered Server busys = numerous "click's" to see same amount of content.
So HC can "claim" to advertiser's an (arguably) mis-representative and inflated number of page retrievals. Similary, the rating agencies that monitor internet page retrievals will be getting false numbers upon which they base the industry statistics.