it would be great be able to tag / limit access by the thread, and have it maybe be a bit more granular. That way we wouldn't have to have so much stuff buried behind the iron curtain. I dunno if XenForo does that by the thread or not, but if it does, I don't think cleanup will be an issue because there are far, far fewer threads in those sections. And some we can just leave in there behind the nsfw-wall
That said, there is a lot of stuff behind the nsfwwall that is all over the place and might contain a broad range of content, with the reasons it is walled off being brief and infrequent but present peppered around.
Another thing is the fact it used to be something people just did to keep literal children from getting involved with plots when we used to let younger teenagers in.