The fact that something is totally obvious is never a reason to not try to go back to the well with some more obvious blogspam.

After enough successful trips they may figure out what their optimal tradeoff is between spaminess and not winding up on the front page.

Take a look at how many articles on the frontpage today today don't follow those principles.

For instance the current #1 post - "Living in a van" - has one mention of Priceonomics in the article, no explanation of the service, and no call to action within the story content.

Not saying that this isn't obvious, just saying that despite it being obvious people don't necessarily employ those strategies and are tossing out a huge number of potential new users as a result.

Users...eh. Signups are not revenue.

[cue 'signups can too be revenue!' HN submission]