If you want NSFW on /c/all it shouldn't take too long to block each community instead - I've done that to most of lemmynsfw and haven't seen anything in a while. Scrolling /c/all in peace is really only an option because Lemmy is so new - if you browse /c/all in a year from now you're gonna get a lot of stuff you don't want.
The app you use can instance block on mobile. Not sure about desktop experience tho. Connect and Liftoff have blocks I dunno about the other applications yet
/uj For what it's worth, as someone who posts quite a bit of stuff there, I also wish full instance per-user blocks were a thing. I like that stuff, but I understand some people don't and rather not force furry tiddies on them. ;_;
/rj But yes, certainly avoid yiffit.net if you don't like that sort of thing. :P
Edit: To those wondering if their instance is blocking it, afaik lemmy.world and sh.itjust.works do not. You can check the instance list at the bottom of the page. Or I guess check if you can see this comment, since my account is on there.
You also won't see furry porn if you have nsfw off in the settings. Or if you don't linger in r/all for too long (there's only like 5 of us posting regularly, it's easy for it to get drowned out).