Actually, once a powerhouse reaches the realm of a God Supreme, detonating their inner world is no longer so easy. While it can be done, the corresponding price is far greater.
By the stage of the God Supreme, body and soul have long since merged into one. Once the inner world detonates, it is equivalent to self-mutilation. Not only must the physical body endure the agony of flesh being torn and bones scraped, but the soul must also suffer the torment of soul-refining.
Once detonated, one dies amidst endless agony, gradually losing consciousness, and even being able to watch one's own body disintegrate piece by piece.
Chapter 3998