There’s some misinformation floating around regarding Lemmy not having a karma system. While many have discovered otherwise, this is for those who may not have.
While it’s not exposed in the Lemmy default user interface, Lemmy does have a fully functional karma system and it is visible in third party clients such as WefWef and Memmy.
Do with that what you will.
What Lemmy does with that score is ultimately instance-specific. Over time I expect we’ll see more differentiation between instances in terms of how they treat things like that.