Ok, so first of all downvote mechanism is a manabar, just like upvotes. In fact the capacity of your manabar is one fourth of the capacity of your voting manabar. It recharges from zero to full through 5 days, just like any other manabar. The only notable difference is that it is possible to keep downvoting after downvote manabar is exhausted, however such operation costs voting mana instead, which means downvoter gives up his voting power and potential rewards from curation (separate manabar was introduced precisely to eliminate that effect, otherwise no one would want to waste time and rewards in order to police the content).
You can see downvote manabar in various places - for example on account page in Block Explorer.
Downvotes are not just for punishing bad actors. They are also used to trim rewards that downvoter finds excessive. And yes, some downvoters use reasons for downvoting that I personally find ridiculous (or are just jerks).
As for the second part - I'm pretty sure every downvoter, especially ones with significant stake, has their own strategy. There is no need to introduce mechanism for coordinated downvoting, although some community moderators might actually welcome a ready to use way to support their efforts. From the whole idea I'd like to see the ability to attach reason to the user that is placed on a blacklist - also front ends should show that reason. That way not only blacklisted individuals can learn why they are not wanted, but more importantly curators might see that they should avoid upvoting certain content - less people tricked into upvoting bad actors means less need for downvotes (and it is also beneficial to curators to know in advance what is likely to be downvoted, because upvoting content that is later downvoted reduces their rewards).
First of all, I'm glad someone who is far more technical than I has given it a look and some feedback, thank you! :D
Secondly, yes I know that it could be something potentially undesired to have it baked into the base layer to override downvote bars. I think the conversation is important though because there is a lot of room to be desired with the current system of down votes. It's why I felt the important need to put my ideas on paper and waiting for some feedback.
I think that your banner idea for WHY someone is on a blacklist or downvote list is really important. That would go a long way to improve the communication in terms of it. A lot of people get added to a list sadly, without much consideration of the negative wider implications of that and how it looks. To someone who isn't well-versed in Hive, it's politics and workings, seeing the downvotes is certainly a turn off especially because there is minimal or no explanation provided at all and it's DEFINITELY not easily apparent to someone like a banner would be.
I think this is exactly why I wrote the post though, to just get a discussion started. We can morph the ideas as things go along but a deeper conversation around them I think is really important for the health of the platform.
EDIT - you have just given me some inspiration to a follow-up to this based on your comment, so thank you!!
That's what saved Hive from bidbots - even though there are still bidbots operating on Hive, they don't just overwhelm the inflation issuance anymore.
You mean maintain the control of governance the oligarchy possesses. Taxation is theft. It's also tyranny in a plutocracy, which is what Hive is.