Leadership training tends to add things: frameworks, techniques, language. Self-awareness works the other way. It removes the friction between who you are and how you are trying to lead.
A leader who knows how much pressure they can genuinely carry stops over-committing and under-delivering. One who knows how they take in information, quickly or reflectively, stops mistaking their own pace for the right pace. One who understands how they give and receive recognition stops being surprised when a team member needs more of it, or less.
And because the profile describes people, not just you, it changes how you read a team. Differences that looked like attitude turn out to be temperament. Conflicts that looked personal turn out to be two natures that need a different arrangement. That is not a soft skill. It is the difference between managing people and understanding them.