LRCC can only be activated on two computers at a time, which probably kills the idea. While you could do what you want via a web browser (logging into the same lightroom.adobe.com account) there's no multi-user control so you'd just be winging it. Joe could change Jane's photo, and Jane would not know and could only reverse the changes the long way. If Jane deleted a photo that only existed in the cloud, it would be deleted forever.
In future, a multi-user LRCC could develop. I wouldn't hold my breath though!