The NSFW stuff was/is a bit more complicated than it might appear on the surface. A lot of instances do not allow NSFW. No judgement, it is what it is. But people on those instances could sub to NSFW communities elsewhere, primarily LemmyNSFW. Less so now, but for a while it was common for those posts/communities to not be tagged NSFW, which caused them to show up on All for people that didn’t want to see it.
Then there was the question about types of NSFW content. Even people that enjoy your standard porn categories had lines they didn’t want crossed in their feed. Specifically animated/cgi CSAM and scat. The former is illegal in some jurisdictions, and caused a different instance (name withheld) to be widely defederated. The latter was more of an issue with limited tools, but the result was the same- either LemmyNSFW blocks that (at least until better tools are available), or they also get cut off.