Are you saying: (1) A bad post is less likely to be read because it will not be promoted and it will be downvoted; (2) Because bad posts are less read, they have a smaller cost than good posts' benefits?

I think I agree with that. I had not considered karma and promotion, which behave like advertisements in their informational value, when making that comment.

But I think that what you're saying only strengthens the case against moderators' deleting posts against the poster's will because it renders the objectionable material less objectionable.