The core problem is not a technical issue but instead an utter misunderstanding of how and why people use social media platforms. They do not go to a social media platform in order to find or be exposed to content that they don't want. They go to a social media platform in order to find, consume, and enjoy the content that they believe should be rewarded.
This is not just a social media designed to leverage the behaviors of people who " find, consume, and enjoy the content that they believe should be rewarded" because on social media like you mention, they have little direct control over what content gets rewarded.
So, let's ask the question from the other side of the coin. Who is it that will have the most use for downvotes?
People who go out of their way to seek content for down voting. People who have been involved in the Whale Wars before and have consistently used downvote vote power to abuse and harass others. People who take it on themselves to go and police others. Bot owners who realize that downloading content which is associated with their bots effectively provides a bit more of the reward pool for themselves.
"In that single statement is why the rest of your post doesn't matter. It's a fantasy. It's a fantasy build on observations about human behavior which no one believes because they are simply not true. I won't say that this is a lie because I believe that you believe. But it's wrong. Elementally."