This doesn’t explain the situation where edits are happening. If I’m editing a wiki post, or a reply from the full screen composer - why would you not have a save button?
When I’m using the full screen composer it’s not because I want a distraction free interface, rather it’s because the normal composer doesn’t let me see the entire post. If the post has graphics or particular formatting, I need to see it full screen. I don’t personally see this has a valid reason to confuse the user into thinking that the edit has been saved. Saving work is a critical functionality.