Boosting threads is useful in that it helps shift a post from 'new' (which most people don't check) to 'hot' (which is the default feed for most people). Posts from small communities often die with 0 upvotes and 0 downvotes without that.
Just did a little unscientific test. Made a post in a community that usually gets 20+ upvotes within an hour. No self-boost puts it at 1 upvote after an hour.