While I don't at all refute that downvote faeries are an issue, I still feel that we could only gain by having guidelines related to what sort of blogposts are encouraged here. Repeatedly, people have asked for self-promotion to be discouraged. Repeatedly, they have been told there will not be guidelines on blogposting.
Taking a quick look at the last week or so in posting, the highest upvoted threads have been ones with interesting news stories, (tax evasion and SL, Twitch not allowing SL streaming), discussion of the second life music scene, and new players seeking (and gaining!) information as they join SL for the first time. In contrast, nearly all of the downvoted things were blogs that contained posts about a particular outfit, or bypassed an official news posting to post it on their own website.
I completely agree with the TL;DR you posted. The downvote button is not an effective way to moderate. However most blogposters do absolutely nothing for the subreddit either. Dropping links without contributing to discussion may not intentionally be self-promotion but it sure appears like that to an outsider.
To be completely frank though, if we want to see this subreddit thrive it needs to see some moderator driven direction.
Here's some alternatives I think would better suit a reddit community than encouraging self-promotion of blogs: