Whether the OP is new to breeding chickens or not is kinda irrelevant. They've already stated the question is purely one of curiosity. A hypothetical question deserves answers, not just more questions. As to why anyone would want to do this, I'd say a perfectly reasonable answer could be as simple as 'Well, why not?' Hobbies and interests are things you should feel free to indulge in without the need to justify your choices or preferences to other people with rational reasoning. Just about ALL of the chicken breeds around today are only here cause someone way back in the past thought 'Hey, what if I cross an X with a Y and then add a bit of Z?' And a lot of the breeds on the verge of extinction are there for a reason. I was reading a discussion on another forum recently, about re-creating old breeds that were long extinct. One particular breed was mentioned. Some people were keen on doing it just to see if they could. Some people said, well, the reason this particular bird became extinct very quickly after its creation was because it was basically rubbish. It was slow growing, too lean to make good eating, a poor layer of small eggs and very dull looking into the bargain. The argument against was fairly persuasive. So if the breed was still in existence today, would we have some kind of moral obligation to keep it going? I imagine loads of backyard hobby breeders have more than one 'new breed' programme up their sleeves. Probably more for their own satisfaction than to have a new breed recognised officially or to make any money from it. Here in the UK, to have a new breed recognised by the PCGB (Poultry Club of Great Britain) it has to have been breeding true for at least four generations, be kept by a number of different breeders, and for all the birds to have been registered with the PCGB and identified with their official club leg rings for a certain number of years. You then have to apply for official breed recognition which may or may not be granted depending on how well all of the requirements are fulfilled. This applies to long established 'old' breeds that aren't native to the UK as well as any kind of new breeds. In fact think most of the 'new' breeds gaining recognition are in fact just old breeds from different countries... I think here in the UK the only people who take out a patent on breeds are scientists doing genetic research. Like the glow-in-the-dark mice.