I think that whales have no idea about how downvotes is an hammer in wrong hands.
If you remember your blacklist recent episode you have to agree that the perception of downvote bad power over people is very high.
Downvote are a bad solution for a real problem.
Let's try to find a better solution.
We think that just do not vote a post is all you need to stop plagiarism and other bad thinks.
If you are a little account and post plagiarized content and have 0 rewards, you will stop very soon.
Downvote can be used to silence, intimidate, fear this is what could happen, or, this is what the small accounts feels can happen.

We are non speaking about reputation, we are speaking about Proof of Activity, a value that allow to determine, in a block of time, how much you contribute to the community.
Reputation is about you are a good guy or a bad guy.
PoA is about how much active you are in a period of time, you can be a good guy doing nothing at all.
How to understand if you use a posting bot?
This is a good question, and is a general problem on Hive and the same can be asked about reputation and any aspect of Hive, until you let people use bots and multiple account I think that this problem can be hardly solved, but we can try to mitigate in many ways.
i.e you can create two types of users, if you want you can have a verified account, that have some privileges or an anonymous account, like now.