He does this... it's really odd.
Well, not so much the fact that he posts more-or-less fully untagged pictures; as the fact that he's so inconsistent with it.
Example; He usually posts untagged/one-tag posts (the one tag often being more-or-less completely irrelevant, as OP said)... but then there are days where he posts pix that are not only abundantly tagged, but often correctly so.
See these two examples from a little earlier today;
xbooru.com/index.php?page=post&s=view&id=240309 xbooru.com/index.php?page=post&s=view&id=240308Really makes ya wonder what goes through his mind (if anything)... lololol.
And to any newbies/less observant people that complain about this to the moderators... don't bother with it.
In spite of the fairly ominous 'tag correctly or you will be banned' warning on the upload page, it's never actually enforced (just poke around a bit on the forums a bit and you'll see what I mean). It's frustrating, but there isn't too much you can do about it short of just leaving... it's best to just ignore it or (better yet) throw in some tags of your own and move on, haha.
Just my two cents on the matter anyway...