Ad buyers require details about the community where it plans to spend its ad dollars. These details include gender, age range, geographical location, etc. Facebook and Google ad platforms are wildly successful because they are able to provide these details and advertisers can expect a reasonable level of success.
Since Steem-based sites & dApps will not be able to provide these details of its members, we will see really low grade and irritating ads that will upset our community.
Desperate times may call for desperate measures - but an ill-conceived ad platform service is probably not one of them.
We can get some good demographics though; e.g. it’s easy for an algorithm to tell whether someone is interested in blockchain or travel, etc based on the tags users upvote or they post using.