I can see some benefits to this.
- nsfw content might now be even more legally protected I the u.s if viewers are defacto 18 or older. You can argue all night if it's moral, but as a varified legal age viewer, no government will show up at the websites door over minors accessing. If you if you don't this this happens look up some of the biggest names cases and questionings and etc directed at these websites.
It might actual get these nsfw a more official standing, as even today these types of sites are seen as small 3rd partys. They don't have apps on Google play. But having these types of things in place might make nsfw sites more likely to get an appstore app in the future.
- If minors cannot just easily join such a site like these, and upload nsfw content, your content is much more likely to be legal viewing privately in your home.