Downvoting is as valid as upvoting as a way to set the rewards. A vote is not just about expressing approval as it has a monetary value too. Adjusting rewards is the only reason I downvote. It is definitely not up to Steemit. They just created the platform and in time they may step back from being the main front end as others take over by doing a better job. For now they hold a lot of Steem, but they have said they will reduce that over time.

A lot of the big bot abusers are well aware of what they are doing and they exploit the system for maximum profit rather than trying to be part of the community. If nobody shows real interest in a post by commenting then why should it be worth $20 or more? The value is up to the community. Unfortunately some people get away with abuse by using bullying tactics, as you have seen. He's hit me too. Maybe the free downvotes will be used by the big silent accounts to address this. We shall see.