I don't know about other breeders but I for one will rather post the moment the stock is available, but to tell everyone I maybe bred ???????? this year, it's a waste of time, I'll rather place a add on classifieds what I have available, I just don't see a use for this. If you're worried about reputable breeders than rather ask admin to review adds before their posted, it will help with scams but it will bump small breeders out of the system. But if I sum up this whole topic it sounds like you want a website in a website, meaning there is a whole history of him/her and what they breed, it's a nice Idea, but each profile is going to need updating on a frequent basis and I do believe that a forum like this do cost a bit to keep running, now everyone want breeders to start their own mini website, it doesn't add up in a bussiness perspective, maybe if breeders are prepared to pay a certain amount each year then yes it could work.
a suggestion from my side is that admin can give a stamp of approval on a add, just to say it's okay to buy from this oak.I think that it's the easiest and simplest solution for now.