This came about based off what I've seen from the show and is meant to counter the idea that Griffons are represented in fanon sometimes as part of a warrior empire.
Griffons are highly independent creatures that have no significant form of a society of their own. Their once prosperous kingdom fell during the reign of King Guto when the Idol of Boreas was forever lost. Griffonstone is the last remnants of what could be considered Griffon society, but it is merely just a hotspot for Griffons, many having homes and remnants there from their families. Most modern Griffons are intermingled among other species. Griffons may mate and start families, but it is usually expected that the pair is the largest and that the offspring assert their independence as soon as possible. Their stereotypical demeanour is one of greed and self-righteousness, yet that is not a trait that necessarily all Griffons possess. There have been efforts to restore Griffonstone to it's former glory, but efforts are futile while the Griffon independent ideology lingers.