It is not, don’t worry. From my POV the UI will be exactly the same, except the action buttons will be removed. And if the permissions are set accordingly, the whole tab can be hidden.
It was not in MVP, so I didn’t give it much priority, but you can check the updated proposal.
And you are not wrong, it is a modification on it just with better visual cues.
We could go this way. The thing with this approach, at least from my POV, is to keep track of different threads that can happen naturally in a discussion. This is a difficulty I have with Discuss as well, mind you. Sometimes the discussion go on 3 different topics, and it’s hard to keep everything in mind if everyone is not very diligent with their quoted replies.
Was this featured missed from XWiki at some point? If it was, then maybe is a good point to go in this direction.
I agree on the sidebar / bottom bar, it was my initial proposal months ago. But it can be a problem when a content related right sidebar is present. You can follow prior discussions on it here