I think it should not be same for all the users. As far as I can remember, I have seen different time for different users but now, local time for all users seems to be same. Am I correcrt or missing something? Is there any recent change on this?
You can set your local time from your profile settings. Maximum people use local time as on forum time to see any post according to forum time. They do not want to miss anything on signature campaign or any other campaign as maximum campaign happen according to forum time. Hopefully think you have understand the reason of same local time of maximum people.