This issue has been raised numerous times, and by some people with high reputations. It's even been emailed to the steemit people, but to no avail. The people who use the downvote button in this way are attempting to censor steemit through intimidation of others by making everyone afraid that they might say the wrong thing and be attacked too. Worse than the money loss on posts, if the person attacking you has a higher reputation, you can lose yours. Some people have been driven down to reputations in the minus range. Once their reputation is at zero, their posts no longer show, so you can see how effective a censorship tool this is. But Steemit seems to like it that way. Makes you wonder about what Steemit really stands for, doesn't it?