An interesting idea, on the one hand I like money and the idea of being paid just for being a member is pretty cool. Not to mention more money for Steem would hopefully result in more and faster development.

But at the same time, I think selling advertisements on the platform disincentivizes people from creating content, and shifts the financial reward engine to one that is focused on account ownership and gaining rep through any means necessary. I recently read the Steem white paper and a lot of what Steem is based on is the idea that users will police each other. The platform is not invulnerable to manipulation and abuse, but the hope is that since everyone is getting paid to not only create and curate content that is valuable to the community, but they are also getting paid based on their contributions weighted against everyone else's. Accounts that are abusing the system will get weeded out by the users who have an incentive to increase their reward percentage by exposing abusive accounts that take at least the minimum SP to comment amount out of the system just by existing. These accounts could pretty easily increase their power through boosters, which would be paid back pretty quickly through the increased rewards generated by ad sharing.

Additionally, it would feel like Steemit would be "double dipping" if they were getting paid not only to run the service, but also by selling their users information (which is essentially the same as users paying to use a service, users are just paying with their information rather than their money). Most services that sell ads as their primary source of income do so because they are a free to use platform. While Steemit is a free to use platform, there is already a percentage of the Steemit reward pool that is taken out for distribution to the developers. While again this is not directly requiring users to pay for the service, it really is since the percentage that is taken out is money that would have been distributed among the community otherwise. If Steemit were profiting off of ads, they would be requiring their users to pay them by giving up a percentage potentially rewards pool, as well as to pay them by selling their information. If that were the case, I think it would really detract from the value of Steemit and depreciate the value of this awesome community.

For those reasons I stated above I would be against Steemit selling ads on their platform, even if they shared the profits with the community.

Great question, it prompted some good thinking and discussion among the community. Thank you for asking it. I'm looking forward to seeing what the rest of the community thinks!