I don't think the term "halves shortage" is accurate TBH. It's literally a halfback shortage. There are heaps of running halves out there, hence why I think clubs would be silly to pay big money for Luai etc. There are very few decent halfbacks, with the genuine ones being the game-controlling type.
I guess there are two main factors - one being that the Under 20's just never had the defensive mindset to need controlling halves, it was basically whoever made the least mistakes and held the most ball normally won. The second being that it takes a long time for them to develop. And by-and-large, they don't want to wait for 5 years in reserve grade, and a desperate team will snap them up with a first-grade contract and the dollars to match. It's a lot easier with forwards and outside backs, you can blood the forwards via the bench, and the outside backs often make up with speed and enthusiasm what they are lacking in experience. Or you can just blood them on the wing. It's not the same with Halves, and while you look at an example like Ben Hunt who was introduced via the bench, and how the time as a bench hooker was invaluable for his defence, that kind of role is only possible if they have some of those traits already.
As much as I hate the Roosters' poaching policy, it seems Sam Walker is one of the few halves being developed properly. It's surprising really, they are known for waving the cash to lure potential stars, and generally demand success immediately. But they are showing an un-Politis amount of patience with him. He's arguably barely first grade standard at the moment, especially when it comes to his size and defensive ability. But I would say they are convinced he will come good, and are looking to reap the rewards in later years. It is going to be much easier for them to find a gun 5/8 to replace Keary as his partner than it would to try to find a complete halves pairing, and while I wouldn't consider Keary a halfback (despite playing in the #7 on occasion), I'd say the Roosters are counting on his maturity and cool head to mentor Walker.
Wouldn't it be fucking wonderful if we were to have the Roosters put in all that effort to develop him and then we bring him back here to partner Mam when Reynolds retires.