It is the race to be on the first page of the thread since it is often the only page that is being read. I'm not sure if the campaign participants today are being mandated to be on the first page of the thread but I'm not gonna be surprised and advertisers would like that.
I think OPs of a thread are to lock the thread whenever it reaches a certain number of pages and his question is answered already. If anyone does have anything else to say, he can create another thread for his issue.
I guess as long as your post is on-topic, that will never get you into a problem. But personally, I also want to post on its first pages so that my answer won't end up like a repetitive one on the posters that have post their ideas ahead of me.