You answered your own question in your 2nd paragraph .
That's why Melbourne has 10 dots and Sydney has 9 and AFL spend 100' of millions trying to get more dots in Qld and Sydney while some people would like to give the more important ones away just to create a more geographical eye pleasing landscape.
The AFL has spent the last 20 years now trying to get more of the Melbourne clubs to relocate.
North Melbourne is probably the Melbourne based AFL club that is struggling the most at the moment, yet they are better off and bigger than even the most successful Sydney based NRL club (or any NRL club at all), and I remind you that despite that fact the AFL has spent the last 20 years trying to convince them to relocate out of Melbourne. That fact alone should be a massive warning sign!
If all the Sydney clubs were thriving then maybe you'd have a point, but they aren't, and the only reason we aren't constantly worried about one of them carking it like we were a few years ago, is because now the NRL is propping them all up. Take that $13mil a year away and half of them are back to being in the shit again.
If the roles were reversed and the AFL were based in NSW and QLD, then they would have spent fortunes trying to crack the WA, SA, and VIC markets, because realistically those markets are more or less just as important markets as the NSW and QLD markets in the Australian context.
Finally, the Broncos, Storm, and probably even the Warriors are each individually worth two or three of the smaller Sydney clubs to the NRL in the money that their presence in the competition nets them in broadcasting, sponsorship, and corporate dollars, similar would be true of any Perth or Adelaide clubs. So tell me again who are the more important dots on the map?