All vote sellers or bots have to do, is reduce the cost for the same amount of upvote % that gives less return, and bring back the same proportions that are profitable... Curation and bots are pretty passive compared to creating content. Clicking with a mouse, or autovoting and selling your vote is what many do to not have to do even a mouse click after looking for stuff to upvote. Money rules.
So many people only care about the investors, trying to draw in more investors. The claims were numerous about how "Great" vote selling would be to draw in more investors. Where are they now? Why isn't Steem filled to the shit with investors who can just take advantage of selling votes rather than give them out for content they want to reward? atsdavids posts is more about that, about how 50/50 is a good thing to try because we need to bring in more investors, because they matter and maybe will want to invest if they can make more with curation... maybe... but like you say, it's another nail in the coffin for the primary app of posting content.