What do people downvote nodes without commenting on them?

I can think of two valid reasons for downvoting a node without comment. Although in some respects they are not mutually exclusive reasons and maybe both conditions should be valid before downvoting.

1. A call to have a node deleted for one reason or another has been made. A certain number of downvotes has to exist before that will happen.
2. Commenting on a node will add fuel to a flame war. If a node is a flame or trollish it could be legitimately IMHO downvoted without further comment.