That's because a non-Sartanian realm helped them out because it benefitted them.
This.
Arcaea wasn't really Sartanian. It was mostly Order of the Elders, until Magnus went on an insane power trip and started abusing his secular power for religious purposes. This got Arcaea pissed at OoE. Sorraine got its ass kicked by OW (who follow some dragon cult), and would have been wiped out had they not signed their sovereignty away to the Arcaean Empire.
Coralynth has never really faced any serious threats. It is completely sheltered by Arcaea. There is no indication that Coralynth wouldn't just flow and collapse like every other Sartanian-dedicate realm that ever existed.
I'm not saying that a realm dedicated to Sartan *can't* be successful. Just that it's never happened so far.
