"Indeed, if you choose to cultivate the Hao Tian Hammer now, you could certainly boost your strength to another level in a short period of time. With suitable soul rings, you would immediately become powerful, possibly even stronger than soul masters at levels 50 or 60. However, have you considered this—what if you start cultivating the Hao Tian Hammer at level 90 and acquire nine soul rings? What quality would those be? By then, it wouldn't be impossible for you to apply nine hundred-thousand-year soul rings to yourself simultaneously. Even if the Blue Silver Grass is not optimal, it will be enough to push you to that level. It wouldn't be too late to gain strength from a solid foundation then, would it? At the rate you are now cultivating, I'm afraid you'll break your father's record as the youngest Titled Douluo. What's the rush?"
Dugu Bo clearly didn't know about the fatal flaw of Twin Martial Souls, but his words were obviously sensible.