Perhaps because since it is a point target while using a stressor, same as the search feature, both are always used to overload a server. I bet they don't want waste the time to turn on-off the feature every week. Turning off the stats is like a permanent fix.
Honestly, I don't think that users' stats are necessary stuffs for most of bitcointalk users; and those stats are not our first priority. Therefore, it is good to see the function was closed (maybe forever) to help the forum operations as smoothly as possible, which in turn bring better experiences for forum users.
Thanks Theymos's great decision.