>>9
It takes 999 sages to do anything. In the time it takes for someone to sagebomb a thread, I can make multiple new ones. Thus, sage is useless as a downvote/weapon/insult.
Sage is polite and should be used when you want to post but don't want to bump the thread. Appropriate uses include replying to a very old thread (necromancy considered harmful), or when your post doesn't contribute much to the discussion.