You can't police downvotes that's for sure. They are part of the platform for good reason, but like with anything can be abused. I think the main issue you have is that when you access steem via steempeak, the downvotes are really in-your-face. However if you access via steemit, you have to actually open up the list of votes to find the downvotes. It's a lot less obvious and most people probably won't even notice them. Therefore I think the issue you have is more to do with the way the downvotes are being displayed in steempeak. I share this opinion and have raised this concern with the steempeak team. They tend to agree and are looking to potentially change it - they are open to suggestions - visit them on discord: https://discord.gg/Fy3bca5