>>95918724
Correct. One analogy I like is think of everyone in the realms as black people, devils as American police officers, and demons as serial killers that exclusively target blacks. Don't let that make you think devils are better, though. Devils and demons are equally dangerous, the former is just more predictable.
Even a common enemy isn't enough to "organize" the tanar'ri, really. Graz'zt, Demogorgon and Orcus are still fighting each other as the Blood War goes on.