It's a system that rewards sticking around for a long time and not just showing up in short burst. People that have been around longer tend to follow those who stick around a long time. After going through a few "game forum phases" you see all the accounts that stick around for a game, post a lot in the forums, but then wonder what happened to them a couple years later. Only a small minority continually stick around for years. You gain more when becoming followed by members who have been around a long time, rather those that show up and will be inactive a year later. Again, all in speculation, I just feel that there is more to this "follow" system than meets the eye.