What functionality is missing? What is unsatisfying with the current situation?

Currently, I can disable Social Media Sharing Widgets on my world if I do not want them available to people who are viewing it. I can have them as teh default, or I can leave them enabled so that some appear, and then customize what does or doesn't appear via CSS. On manuscripts, at the bottom of each chapter there is a "share to X" link that I can't remove via the settings, but I also cannot remove via CSS because we can't add CSS to manuscript pages. My request would be that we are able to toggle social/sharing buttons "off" in our manuscripts just like our worlds. An extension would be the ability to change what social/sharing sites are linked in our manuscripts if we do choose to have buttons displayed, but a minimum would be an on/off ability.  

How does this feature request address the current situation?

While I have quite a bit of control over who can see my manuscript, from fully public to fully private and many sharing/privacy settings in between with user groups and such, I don't have the option to remove this button that encourages people to share the content to an outside platform, or even to change which platform people are encouraged to share my manuscripts to. Personally, I don't use X and I don't want any of my intellectual property on X, and I don't want to encourage people to share my stuff on X by putting a button there for it. For some of my works, I wouldn't want to encourage people to share it outside of WA at all. And I understand that if it is public, I can't prevent them from just sharing a link on their own, but I think there is a big difference between someone deciding to share a link and someone being presented with a button encouraging them to do so, and I'd like the ability to disable that button.  

What are other uses for this feature request?

I'm not sure there are other uses for this feature request.