I've spent the last few days in Melbourne and have witnessed first-hand why the VFL's centralisation strategy works so well. Most of the suburbs represented by clubs are close to the CBD. And the two stadia are well-positioned near major train stations to help fans from the outer suburbs.
Compare this to Allianz which is a 15min uphill hike from Central. Not only that, but as some have mentioned, Sydney is a much larger city by area. Manly's far from Moore Park, ditto Cronulla. And Penrith's further still from ANZ.
The best scenario you're ever gonna get is Souths, Roosters, Parramatta, Wests, and Canterbury playing out of ANZ/Allianz with Penrith, Manly, Cronulla, and St George playing only 1-2 of their home matches in the big stadia.