I have completely no involvement in this nor am following any of this at all, but I've seen mentions of tag wrangler burn-out months and months ago. The fact there even needs to be a tag wrangler position is very shortsighted, since it's a non-scaling solution. Also, with the AO3 codebase, it seems like there's only a handful of people having to write a huge laundry list of features. When the whole Delicious/AVOS thing went down, there was a lot of "Yeah let's add more bookmarking features to AO3! ... but not within the next year because we don't have any time".