EDIT I was wrong! Lemmy does have karma, even listed in the API, though for some reason it doesn't show this to you itself. So, those of us just using Lemmy directly have been under the mistaken idea that it didn't do it, and those using third party apps are seeing it: https://lemmy.world/post/1250922?scrollToComments=true

~~That's interesting, because on the Lemmy website, there is no total upvotes number visible. It only shows the total number of posts and total number of comments. It then shows the list of posts and comments, and you can see the scores for each, but there's no total. Memmy must be calculating this itself. This seems to be something third party app developers are adding which is not present in actual Lemmy itself, in order to try to replicate Reddit Karma somewhat.

As Lemmy works itself: On Reddit, in addition to your posts and comments having visible scores, your username also has an aggregate score, which Lemmy does not have. At least, when I go to your profile, I can see the scores for your posts and comments, but I cannot see any aggregate score for you as a user. That's what Reddit Karma is. I don't know what black magic formula Reddit calculates it from, as old Reddit and new Reddit show different Karma numbers for the same user, but whatever algorithm they use, it's an overall user score that Lemmy does not have (so far, at least). ~~