Currently Collaborator only supports one thread of conversation per document / code location. This makes it increasingly difficult to track the individual threads when multiple unique comments are added to the same location (or overall) & replies start coming in.
Adding this could also provide opportunities to reduce the number of email notifications coming in for some users - for example, only notify me when someone replies to a comment / finding made by me. Note that the software would still need to consider some review templates / role types, for example moderators who are required to read all comments.