You don't but I did because I got tired of having to update this small code snippet every time we added a forum to the system. So this way, I added a couple of fields to the table and set them when I create the new forum and everything just adjusts around it.

We currently have 19 public forums and 6 private forums for community Management. There are also 9 categories. If I add more (I have two forums that could be broke up right now) then I would have to change the code, however with my method, I don't. This also makes it easy for the other Administrator who doesn't touch the code to know that things are kept up to date and allows our Network Administrator to know that the listing is correct as we want it.

p.s. The other field I added allows you to turn post counting on and off per forum.