I use it all the time. I check the ranking, click the graph and see how they fared over time. Just the other day I checked and saw that when Dixie Dash was actively posting on the board she majorly spiked in popularity. It has, of course.. gone back down quite a bit.
I check major names if I'm on their links like Jenna Jameson, etc. Check my favorites.. hell, it helps quite a bit to know whether or not I should even TRY to search for someone in the 'find your favorite' forum if they have maybe a dozen links, barely any popularity in the graph and no profile picture or a homepage to visit.
Usefully useless info. On a porn forum, there is no porn stat that could be labeled useless.