1000% agree.
In particular steemit.com has to start burning steem because they set the example for everyone. If steemit burns, everyone burns. It doesn't have to be ads, it could be promotion spots on the trending page, instead of a separate promotion category which no one sees.
That way they can keep advertising revenue. But of course to do that they will have to stop bidbots, since people will never pay when they can top spots for free.
Soooo the solution might be to make it mandatory for bidbots to burn 30% of their rewards or something like that. If they don't, then @yabapmatt could remove them from steembottracker.com and Steemit, Inc could downvote all the posts the upvote, making them useless.
This is centralized, yes, as it uses Steemit, Inc's stake. But effective.