I don't know if that's true, plenty of people come from north of Taupo to study in Wellington, why would football be any different?
Alot of Cantabs I know hate Auckland, and have been to visit Australia more than NZ's biggest city. Those with kids would I feel rather have their offspring live closer to them in smaller Welly. Big bad Auckland might as well be the moon.
And then on a pure football development agenda, at which club is a young talented kid currently likely to debut first? The Nix every time.
LBS from the Waikato was courted by AFC, but the Phoenix won his signature, and he's already had significant mins this season. More if not injured. At Auckland he would barely have played this season if at all.
If AFC keep most of their current squad next season, it's gonna be the same. Limited opportunities, for young U20 guys. Until their Academy is up & going fully, it could stay that way. Esp as you feel they are heavily focussed on immediate success, and winning trophies.
I just see it becoming a de facto, split of yeah Taupo north re youth recruitment. With more northern youngsters heading south to the Nix than the reverse. Just because some kids & their parents will feel the Phoenix are more likely to debut young players a bit earlier.
And everyone is in a hurry. Remember the rumours about GSR's Brazilian dad (who is a football coach in Hong Kong), reportedly asking the Nix to give him mins, otherwise the family would look to send him to an overseas club. Some story like that.