Thanks for this post.
I agree with you that these downvote armies are a problem, and that they could become a HUGE problem.

"The accounts don't have any SteemPower at the moment, but just imagine they start upvoting each other and start using that against defenseless Steemit members!"

I don't think they can upvote each other, because part of their strategy is to not make any posts or comments. This keeps them partly anonymous, and prevents their targets from being able to retaliate or communicate.

I think they're all owned by one person, or small group project. The ones I'm talking about all have about 25 rep (new accounts with no interactions), silly nonsensical names with 5-7 characters, 0 STEEM, and 15 SP delegated from Steemit. That means these are free accounts that Steemit manually accepted onto the blockchain through their account creation process.

Even though these bots can't upvote each other or themselves, they'll still grow, via curation. They can upvote other people's posts/comments (perhaps the posts/comments of their owners). They will also get a trickle of interest, memo dust, and so on. It will be slow, but it puts a clock (timeline) on the blockchain. At some point, this army will prevail, unless something happens to stop it.

Their goal appears to build a completely free, and always-growing, massive downvote tool that has thousands of working parts, can survive rule changes or community blowbacks, and can be divided up as needed to pick off multiple targets every day.

@hyjuki and @criblo are the 2 bots currently downvoting my posts. And there's nothing that can be done about them except try to ignore them.

I notice that several of these bots, when they joined Steemit, immediately used their witness vote to cast a vote for @Curator. Curator is a new bidbot, part of the #NewSteem cult, a downvote-for-hire project funded by all the NewSteem whales and dolphins. It's creepy that whoever runs this downvote army seems to fully support Curator, for some reason. By the way, I am on the record for having criticized Curator's strategy/motivations, and wouldn't be shocked if they considered me an enemy, just sayin.

I feel somebody or somebodies is/are using HF21's rule changes (ie: free downvotes) to rig the system and take down parts or all of the blockchain. I can see where it's headed if something doesn't change. You're right to sound the alarm on this as it has the potential to bring everything down, even faster than other existing threats to the community/chain.

EDIT: @trimesgi, @ketszy, @jupyoho, and @hiluop have also locked their leech-vulture-vampire teeth into my flesh. Fuck you, cowards!