Why are this terms still used when they are not canon? Outer Gods and Great Old Ones

[Tou_aperceber]

Lovecraft never referenced to them as “Outer Gods”, nor as “Great Old Ones” used to talk of the gods, simply referring to Cthulhu’s spawn. Isn’t this from Chaosium’s game? That’s like, not canon at all.
Those who live in the boundless void are simply and always called the “other gods” or “Ultimate Gods”