One I raised in a reply was that any random oligarch with an NGO (Soros anyone?) agenda could buy a few million worth of steemit and staff it with a cyber downvote squad to suppress alternative narratives.

Yes, that can and likely will happen at some point.

The only HOPE there is that purchasing so much steem drives the value of all the steem those of us that already have it up. You could power down. Such activities of down voting would likely drive some people away and cause steem to drop. You can wait for it to drop and buy more with what you powered down.

Also it is easier in the blockchain to PROVE they are doing that, and if need be to group counter up against such activities.

That said it's a pretty new world here... with it will come new problems we haven't even experienced yet.