You must break the old to form the new. This was a rule that never changed since ancient times!
This rule existed in many things, and as people slowly found this rule and made conclusions about it, they came up with this phrase.
With the Candle Dragon's blessing, Su Ming could be said to have gone through a strange change that no one had ever experienced before, and that change was this - failing after trying to break into the Berserker Soul Realm the moment he reached the pinnacle of the Bone Sacrifice Realm and not dying!
While this sort of thing had indeed happened a few times in Berserker history, but every single time it happened, these people would lose too much of their life force and would sink to become a mere mortal.