Thing is that being one of those getting in the way of bad behavior is not rewarding nor favorable. No one goes and tells the downvoter good job on making this place better if they've been using it well because they don't want to get involved in unnecessary drama and potentially in the sights of the downvoted user looking for retaliation.
The fact that downvoted rewards go to everyone is not something everyone notices because it's so small. If it was just us two posting on Hive and I'd self downvote my posts because I felt they're too rewarded compared to yours then the amount I'd downvote would directly go to your posts, thereby increasing your pending rewards by that much. However this is not something people notice due to the very limited amount of rewards that do get downvoted in general.
Just a few weeks ago I went and downvoted a user that was posting 2-3min clips of one event she performed on to make it last for 2 posts per day for 2 weeks all getting the same voters to a sum of $30-60 in rewards with 0-3 views per clip on youtube, 0-3 genuine comments per week on her posts and 0 comments of her own in over a month and all I got back was hate and drama and some people losing their minds in my posts about my actions. Why should I spend more time protecting the reward pool if there is nothing but drama and a bad reputation to gain from it even if uncalled for?
That's one of the big solutions we have to fix without making it so that people start overusing their downvotes for personal gain.
That's why it's crucial to address this issue, because discouraging a bad behavior must be rewarded and looked favorable. I guess that lots of other users are tired to look elsewhere to avoid drama and/or retalation.
And that's also why there should be public and generally approved guidelines, because none likes to be downvoted without knowing the reason, while most (reasonable) people understand a downvote if the downvoter shows them that there's a reason (which can be checked and it's not someone's very personal opinion).
We might even use something like the proposal system to write some guidelines and have them approved by the stakeholders: if they get above the return proposal, that would be the proof that the community approves them. If they don't get there, that means that they should be changed to meet the expectations of the community.
Maybe there are even better solutions, but right now it's very easy for a lot of people to ignore Hive-etiquette, as it isn't officially written anywhere. It's also easy to get angry and make a lot of drama, because downvotes can easily "feel" personal if none can point the downvoted author to something written and approved by the community clearly saying that he/she shouldn't be doing something.
Also, to avoid retalation and/or people feeling uncomfortable downvoting someone - I know what downvotes really mean, yet I admit I would still feel "bad" for downvoting someone: maybe "downvote" was a poor choice as a name or maybe we all tend to link that action to a dislike - someone could create an account whose purpose is exactly doing that: not nuking to zero rewards or acting like a sort of police (we already have that), but acting like a curation account.
You self-upvote? You might get a downvote equal to your own upvote. You vote-trade? Same as above: you get a downvote that counters that action. You are clearly splitting an event/argument in 20 short posts to reap 20 times the rewards? You might get a downvote to remember you that this is discouraged on Hive. Of course only if this actions are considered "wrong" by the community, not only by me and 3 others.
You are right and that's why this is a "battle" that should be fighted by the community as a whole, not by some lonely brave users who "sacrifice" themselves for a greater good.