why would anyone obsess about tracking down which account liked which post?
Normal people wouldn't. Unfortunately, there are a lot of assholes, stalkers, and people who are salty they got downvoted and want revenge.
Ever seen people on Reddit say "Whoever downvoted this, go fuck yourselves?" I can guarantee that, if they knew who downvoted them, they wouldn't keep their reaction contained to an edited comment.
Throwing my vote in for the right one too. It's adorable. I mean, the left one is too, but the right one is more adorable.