Has there been another MMORPG with a similar vassal/monarch system?

I know lots of MMORPGs have guilds. You pretty much invite them and if they don't contribute they are ignored or kicked.

What was great about AC was that I felt like I owed my vassels something. Instead of the other way around.

Except for on DT then it was swear or die. Or send nudes and you can join us.

Has there ever been another system like ACs monarchies?