all good dude, it's easy to get that confused. lemmy.ml is actually just one of a number of websites that make up lemmy and the fediverse at large. while you interact as a user almost exclusively through your home instance, much of the content you can access is actually hosted on a different website, even though you still access it through your home instance, think if it like email in that sense. even if you don't have a gmail.com email address you can stil send and receive emails to people who do. that's why my full handle is @this@sh.itjust.works, yours is @Marv@lemmy.ml, and we are communicating with each other on a public form via the individual websites our accounts are hosted on. If you have ever used or plan to use mastodon, that works the same way and actually uses the same protocol (activitypub), there are also other currently less popular social media alternatives that use this protocol as well as speculation that it may be added into some mainstream social media platforms(though I wouldn't hold my breath on them federating with lemmy/mastodon). If you ever join a smaller instance (which I and the devs recommend to help the network scale better), you can use this link to find communities on other instances(they won't show up on your home instance if no one is subscribed to them or they are blocked by your instance): https://browse.feddit.de/

I'm just going to take your response literally, because I honestly can't tell if you're joking or not. when you join a lemmy instance, in OPs case, lemmy.ml, or in your case, lemmy.world. your profile is hosted on said instance, and therefore anything you put on your profile is subject to the rules of whoever owns/moderates that instance. if you don't like it, move to another instance, or start your own, that's the benefit of a federated system!

There is one now, there wasn't when I wrote that comment like 2 weeks ago lol. The nsfw part of reddit seems to be embracing lemmy pretty quickly now that its up.