I think the one thing lost on people is the Swans are the biggest sporting team in Sydney, because millions in Sydney support them as their team in the AFL.
However, 99% of these people are secondary supporters, who are drawn from mainly NRL fanbases. These people are fans of the SYDNEY Swans as their home town team, and are not fans of Australian Rules Football as a sport. Thus, unopposed big Swans games should theoretically get big ratings and sell out based on NRL fans who dig out their 2012 GF scarf.
Same with Storm in Melbourne...Roy Morgan says they have over 1 million fans, but 99% of them again would be secondary fans who are primarily AFL fans. Storm ratings were 608,000 for 2020 GF in Melbourne, and their home prelims historically attract 28-30k, yet they don't sell out every regular season game.
CASE CLOSED