For the uninitiated, generally NSFW is for sexual contents and NSFL is for gory contents. People may want to see one but not see the other at any time for any reason. I have seen this feature requested over the years in Reddit but it never happens. Maybe now some instance can finally implement it?
Why would you need a category in addition to a tag?
Just a thought. Some might need finer details vs block whatever its marked NSFW.
Wouldn’t a specific tag provide enough detail?