Pretty sure the unique shape of KP hasn't changed much since then.What are you on about, what was St Kildas home ground in 1973? Oh yeah Moorabbin, then decades later it was Waverley... And the rest of the VFL teams at the time and their respective home suburban grounds?
Nor has the fact Geelong do most of their training there (even since Deakin)
It's only 6 metres wider than the legislated minimum (116 vs 110), so even in the days when everyone had their own ground, the unique shape compared to other grounds would've helped
But of course that difference is magnified since the 90's and 00's when all other suburban grounds disappeared for MCG and Waverley, then Marvel, with training at KP too and the relative rarity of opponents playing there