Because they're humans, and humans as a general rule will abuse any system they have access to. Not every individual will, but enough that it's a valid concern.Why would anyone abuse features on a fish keeping forum. ? Maybe you are just misjudging the fantastic members here
Though I agree I don't see how a little bit of "splash text" could be abused any more than the rest of the posting system (as long as it was properly validated as not including cross-site-scripting or embedded scripts and such, as any other user-submitted content should be). The worst likely abuse, then, would be someone using it to post rule-breaking derogatory content, or impersonating admins...and that should be easy enough to ban for after being reported/observed. -shrugs-