I think the main thought is to protect the interests those who pay the $25 to have the For Sale venue uncluttered by a hundred CL, Kijii, BoatTrader ads.
I spent countless hours looking for a 21, so I get your point, but the rule makes sense.
Perhaps a SeaCraft Wanted forum, also at $25 per post would be equitable and save searchers some time. I'll leave that to Trayder and The site Administrators discretion. Gotta admit I wasted a lot of time on CL trying to find the proverbial needle in the haystack. It's not always the kill, but the thrill of the chase...