Melbourne, Roosters, Broncos all reign while having grossly perverted Salary Caps.But some have natural advantages/ disadvantages. The teams outside the capital cities (Sydney, Melbourne and Brisbane) seem to have longer periods in the doldrums.
Warriors, Cowboys, Knights, Titans, Raiders are more out of the top 8 than in over the years. This year 4 of them could be realistic chances for top 8, which is good for the game.
Travel is a factor.
But two of the three most successful modern teams are out of Sydney and cheated the cap. The most successful recent team in Sydney....Cap cheats.
Souths had a good run while they employed a suspicious looking roster.
The Cap is the reason teams dominate more than any other reason.