Some people use NSFW tags as spoiler tags, so possibly. There's also varying definitions of NSFW (language, news articles that might be upsetting, etc).
Agree, there needs to be more granularity with post tagging.
Best compromise I've found is using a Lemmy UI that will blur NSFW stuff and let you click to reveal it. You can also block porn instances / communities if you don't want to fight through those (browsing /all on many instances is a minefield of porn lol).