As a good example, I remember a whole string of great Priceonomics articles showing up on HN—well-written, interesting investigations into cool topics. They might have been part of a content marketing campaign, but they were also consistently in the top 10% of articles I saw on the front page.
dang and the other moderators are happy to update submissions to original sources when folks leave a comment and the original source better satisfies HN's goals.
But I do acknowledge that's a relatively recent change (last few years).