Even if they connected people who said they were going to write treats with posted treats, there's no guarantee that they would identify the right people. I'm sure plenty of non-coalies read the letters post or check out requests when madness opens, which means you could have a Non Coalie writing treats for a letter/fandom a coalie said they would treat. Unless someone specifically posts every detail of the treat/fic they're going to write here, there's no guarantee of correctly linking people.