There is already a total count of up- and downvotes, but please never add karma to Lemmy. We don’t want to deal with karma farmers and minimal karma requirements to post. I don’t care about the moderation issues because karma brought more harm than good. Please never add that bloody dreadful thing to Lemmy. I already saw a bunch of people supporting adding karma to Lemmy, which will turn Lemmy into a cheap Reddit clone and karma-farming hell. Please, never add karma to Lemmy. I beg you. No more karma hell.
The votes were not equal to karma. Karma wasn’t just subtracting downvotes from upvotes. They made a function that not every up- and downvote changed karma. It was a weird mathematical function. Karma was also used to limit you from posting on some subreddits. That’s the reason why I heavily dislike karma.
Karma was originally visible raw upvote / downvote tally. Reddit just obscured the upvote and downvote numbers to discourage manipulation for karma.
Limiting participation based on karma didn’t happen for a long time. By the time some huge subreddits took that step, it (or some other gatekeeping) was necessary to filter a lot of malicious users.