I get the desire to limit demographic data of users to advertisers. I also understand the idea of an NDA to keep advertisers from telling other advertisers (as third parties). But I don't think it would work out in practice. It'll just create a kind of arbitrage where demographics will cross boundaries (similar to trade arbitrage).

I really liked this idea of "This is why the viewer should set the price." You were talking about demographics, right? But I wonder if there's a way to get steemit or the systems under the hood to only display posts written by authors who have a certain amount of STEEM Power.

Maybe this option would only be applied to certain sections. The idea is that an advertisement post needs to have a stake in order to get our attention. But in a way, that is what Post Promotion (currently broken) does.