> "...comments like "lol" or "That's the dumbest thing I ever heard" teach us nothing.
> Empty comments can be ok if they're positive. There's nothing wrong with submitting a comment saying just "Thanks." What we especially discourage are comments that are empty and negative—comments that are mere name-calling."
This effect has been linked to polymorphisms on the A2a receptor gene (https://pubmed.ncbi.nlm.nih.gov/12825092/).