Why was the blessing Hatov Vehametiv instituted in Birkat Hamazon but not in Kaddish?

This source-based Torah study examines: Why was the blessing Hatov Vehametiv instituted in Birkat Hamazon but not in Kaddish? It follows the canonical Hebrew discussion through the parasha and classical Jewish sources. This localized discovery layer is a concise summary rather than a full translation of the article; practical, halakhic, medical, legal, historical, mystical or empirical claims remain source-framed and subject to the canonical review status.