What on earth are Highlights? I’ve got a couple which I imagine is a good thing, but no idea what they are, or what got highlighted.
I believe it’s when someone is on your profile page and clicks “highlight posts.” All your posts will appear highlighted green to that person.
EDIT: yes that seems to be it. In other news you can highlight yourself 
I also think that if you give a person a certain number of medals then their posts will be automatically highlited for you. I think.
The downside would therefore be the number of people Ignoring you… 
People who you’ve highlighted - given enough medals to - have their posts shown in green. Also toggleable per profile.
Usefulness: when a thread is all green I know it’s quality ;D