There are a few SPG properties where the breakfast served in the Club lounge is a paid item and usually there are some available items which are prepared ala carte... the San Christobal Tower and the Westin Cape Town (former Arabella Sheraton) comes to mind .. the breakfast at the latter propery incidentally is very good and well worth the charge.
So in fact not ALL club lounges have complimentary breakfast for Plats and/or guests staying on club floors.
mike