Downvotes can be abused, but they have already done a lot of good. Hundreds of dollars in rewards have been returned to the pool instead of going to people who just milk them with self-votes or buy buying votes on junk posts. I could find you plenty of examples. I have seen some people threaten to 'rage quit' because they got flagged, but in some cases they bought massive votes on low quality posts. That is not good for Steem as it sets a bad example. Some of the vote sellers are not happy either as they are losing business, but they will have to adapt. There are still ways to make money.

No system is perfect, but this is what we have now.

I have not had them lately, but your transfer memos are a form of spam. If you have something to say then make a comment and take the risk on it being downvoted.

It looks like you were just downvoted by one person with multiple accounts.