There is one thing I do not understand. If the goal is to make this a front end editor, then why isn't it a front end editor?

It's one thing to say we will have an editor that "looks like front end", versus an editor that actually activates in-place, while a logged-in user is on the front end.

Also, the goal of collaborative editing on a page while locking/unlocking elements on the page seems to be a pretty narrow use case. Is this really a gaping hole that users are begging for?