The comment isn't moderation. It's a signal to other readers that 80% of the links submitted by this user [0] are for this user's own blog. Actually 80% is just for the first page of links. The second page is 90%! HN benefits from variety.

[0] https://news.ycombinator.com/submitted?id=edent

Asking him politely is more efficient than merely downvoting. That way, he can be certain that some people (at least two people, counting me) are displeased with his spamming the community.