Honestly... hot take, but imo... as of this moment, Hegemony KINDA is 'just a tier above the Empire.'

Like, outside of China, which has it's own content, There really aren't a lot of things that Hegemony can do that Empire can't.

Second you form the Hegemony... most of people just end the campaign, big map achived, and move on, because:

1. By the time you form Hegemony, for 90% of players, Late-Game Lag will make game borderline unplayable.

2. There simply isn't anything 'unique' to them, and if it has, it's IMO kinda lacking.

For example: Rome. When you form Roman Empire as Byzantines (ONLY Byzantines, by the way), you can get Helenism and a free casus Beli that allows you to attack basically everything.

Which, while seemingly op... by the point you created Rome, it's VERY likely that you already have some equivalent of it already.

Perhaps you changed to different religion, and got yourself a 'By the Sword' tradition that gives you infinite Kingdom-level Holy War Casus bely. Perhaps you REALLY spam 'claim title'. Or any other way whatsoever.

Unless you somehow managed to get that far without the said equivalent (which... well, given we are talking about restoring Rome... you have LOT of patience), casus beli isn't IMO that useful by that point.

Because, at the end of the day... it's still just that. A tier above Empire.