I think having some form of “I agree with this” or similar helps to make you feel engaged with the content (for better or worse).
I think perhaps the actual person responsible for the post or comment shouldn’t be able to see the results, though, otherwise it just becomes another ego building thing, and you see people strategising explicitly to build karma like on reddit. instead, the author should see a rating, like “slight approval” “mixed feelings” “strong dissent”, etc.
OpenTTD FTW