Thank you for your explanation @biophil. I'm glad that formula changed, because that formula would make the reward pool abuse mathematically possible.
With the current system, all the bot promotions start with a loss. They can turn profit, only if other than the promoters vote the content.
In other words, if no one else than the promotion team upvotes a post, they are guaranteed to have a loss in Steem terms.
I will need to chew on this. Replying to your post...