I think, That they use it to get more people to see their posts.

It's kind of like, posting on a thread to make it go up to the first thread on the page, if that makes sense.

^ good explanation!

The more recent a post is, the better it is displayed on a thread list/section. If you go to, for example, the trading section, and go to the last page - it is the oldest thread. If you posted in that thread, it would have the most recent post in the section and go all the way to page 1 in the trading section/thread list.

^ and it would also be gravedigging XD

True.. I'm just trying to explain it .-.

Yeah, was trying to make a joke :3

Oh...