Not saying that our mods here aren’t doing a great job! Just the opposite! I think they are doing a phenomenal job! However, as users we should keep an eye on the logs to make sure power is kept in check. You can always view the modlog at the bottom of your browser window!
Instance admins have the database and up/downvotes are stored there. Even if they don’t see it directly in the UI, it’d be trivial to extract the data with a simple db query.
The important part: Reward/Penalty is vital for social network adoption. While it’s not vital to anyone, it’s the only way to check, well, your karma (in relation to other users) at a single glance.
Also people are dopamine driven. I honestly doubt that even you weren’t even a bit happy when you saw a post getting many upvotes additional to positive feedback. Or maybe surprised, when you suddenly lost a lot of karma for some comment you did with best intents. It’s quite hard to check every past comment/post, so the total sum makes sense.
Also it’s a good mechanism (not perfect for sure) to assess a user. E.g. some subreddits had a minimum karma limit required for posting/commenting. This led to karma farming and made it A LOT harder for bots or trolls with a gazillion accounts.
Fair enough. I’m solid pro. We already use karma to sort posts and the data is there - just hidden. The upsides weigh heavier for me than the downsides.