It does seem strange that in today's world of Audio Systems and Room Set Up for the use of the Audio System, with the intention to get the best from the End Sound able to be produced, that the term Bookshelf remains in use for a Speaker.
Does anybody actually propose that a Speaker has a placement on a Bookshelf?
Does anybody with a Bookshelf consider it the place to seat a Speaker?
Using the Term to give a outline of a Cabinet Dimension can easily be described in another terminology.