It was precisely because of these various reasons that Priscilla's actual control over the entire Demon Realm was not very strong, and could even be said to be on the weaker side.
Currently, the areas truly under Priscilla's control were actually just the Demon Lord's Castle located in the north-central part of the Demon Realm and its surrounding regions. Further out were the autonomous territories of the various demon race representatives, and then there were the special races living on the fringes who didn't give a damn about her as the Demon Lord.
The Demon Lords before her either didn't care about their control over the Demon Realm as long as they could get troops, or had the intention to manage but lacked the ability, or took the wrong path and suffered backlash. In any case, the entire Demon Realm had been in a state of chaos and disorder throughout its long history.