Isn't Karma essentially just the delta between upvotes and downvotes you get with some sort of weighting thrown in?
Because you can very much get that delta on here, it just isn't visible in the default Lemmy interface. If you look at your account through an Mbin frontend for example you can see the "Reputation points" value in the sidebar: https://fedia.io/u/@wittycomputer@feddit.org