There is a benefit! I know it is a bit convoluted, but I'm working on making this more clear.
- Each character has a list of every unique boss they've defeated.
- Characters get +1 Boss Point per boss on their list.
- Additionally, they get +1 Boss Point every time a boss that is on their list is also on another character's list.
Find how many Boss Points you're getting from other characters by clicking on the Info Button on the Augments page.