They might have played in the top flight of QRL, but not the top flight of ARL/NRL, they aren't an established brand at that level. Same goes for SANFL clubs like Norwood, they might be powerhouses at SANFL level, but basically no one knows who they are in the RL states, do they?
Manly, Penrith, St George etc are established NRL brands. If you were expanding into Sydney now, you would likely never call new teams anything like St George, Penrith etc, they'd get names like Western Sydney, Sydney etc, but that's how the brands have been established and are known at the top level as. I don't have any connection with Melbourne, but I'm aware of and familiar with brands like Collingwood, Richmond etc as they've been top level AFL clubs for my entire life.