One of my issues with likes/dislikes is that it can get skewed so easily. At least it likely wouldn’t happen as rapidly here as it does on bigger boards like Reddit or Imgur. On Reddit my Karma is about 10k, on Imgur I have about 20k points. You get an automatic upvote for each post, but I’ve probably posted less than half of those 10k/20k numbers. It’s just that a few random posts got some traction and accumulated a few thousand points.
Of course, OTOH, maybe likes/dislikes mean more than simple post count.
In any case, what you could do, if people were willing to put in the extra work would be to create a thread called “Like” and one called “Dislike”. If put a link in one of those threads from a post you like/dislike, it’ll say “Like” or “Dislike” under the post.
However, I don’t know how discourse handles multiple people linking the same post in the same thread. Does it just show up once? Multiple times?
I suppose if we really wanted to run with it we 'd have to have some forum full of “Joey_P Likes This” and “Joey_P Dislikes” this threads for each user.
Or just say Thanks.