I think "someone posted a useless (thanks, cool story bro...) comment" is applied too liberally. Downvoting can definitely discourage participation. For that

I think "someone posted a useless (thanks, cool story bro...) comment" is applied too liberally. Downvoting can definitely discourage participation. For that reason it should be targeted towards stuff in (A). Except in the most egregious instances of (E), when people downvote they come across as being immature or petty.