both complimenting or saying shit about one's art with a short comment or a single phrase is really annoying to the artist, most of the time. Toribash community isn't the only to adopt this system, I've seen it in almost every community that has some base on criticism.

May not be the case for you but usually people post their works expecting a well constructed and detailed comments analysing what they did, besides this being really cool to have in your board, this will help you to improve with the others opinions about your negatives and positives explained in detail

I think this "over-moderation" is really useful to the artists