Posting the same, or a very similar thread in more than one forum is against the rules. If it were allowed, then the forums would simply turn into a "screaming contest". Everybody would post the same message multiple times in multiple forums to get greater visibility, and when the thread scrolls off the front page, they would simply repeat. Considering that each message takes up some disk space (on a server that somebody has to pay for), even small messages re-posted multiple times gets to be a burden. So, the only way around it is to force all users to post one thread about a specific topic. That forces people to put their message in the appropriate forum.
It's nothing personal, but it is necessary.