I just tried to "like" someone's post, and it worked fine.
Then I tried on another post and it failed. It said something like you've already liked this post please wait 24 hours.
I tried it again, and it failed.
A few minutes later I tried to like a different post and it was fine.
Does anyone know why or have the same problem?
You probably tried to like the same user that you already liked. You can only change a user's karma once per 24 hours, regardless of how many different posts of theirs you try ;)
Oh thanks. That's why.
I'm assuming that's to prevent someone who is angry or malicious from destroying someone's karma.
Or making karma useless by just liking everyone's post. I mean, what's the point of karma if everyone can just get more by posting more stuff? I guess that's another reason the person who liked or disliked a post isn't shown. Then people can Ike or dislike without being biased toward like because they'll be liked back, and away from dislikes because they don't want to lose karma.
You are correct on all of that :)