While I don't think every instance needs to host everything, I think the most popular instances being a bunch that don't host NSFW and one that only hosts NSFW is an issue. I don't blame instance admins, as NSFW content introduces additional difficulties, but it still doesn't necessarily look the best.
I know the going advice is "choose a medium popularity instance" which I did, but it took me a while to find one that allowed NSFW but wasn't NSFW-only.
I think this is for the most part true. The user should get to decide what to subscribe to and what to block. I think that having instances that are safe for work while others that will host everything else would be beneficial. It would almost be like having 2 accounts but not having to bother logging out and logging back in. That way if you are in a setting that let's say porn popping up on your screen would be an issue then you just switch instances to the safe one.