Something big is happening, as Reddit seems to have purged literally every NSFW sub they know. Reason is always "unmoderated" despite some of the banned subreddits being fully moderated.
Edit: seems to have been a bug in automation (thanks @[email protected]):
https://old.reddit.com/r/ModSupport/comments/1ii67mt/_/mb3fewv
It's still a good reminder on how quickly a community (or communities) thousands of people enjoy and in some cases rely upon can disappear.
It's only a matter of time. They don't display any ads on nsfw subreddits currently, so management likely sees these subreddits as nothing but a cost, especially because they tend to be heavily image/gif based. what they are unsure about, which is why they haven't been purged yet, is likely how much traffic to non-nsfw subreddits nsfw subreddits drive. I think we are likely to see purges of them when/if ad money dips or plateaus and they turn their eye to minimizing operating costs.