Does not matter.
If you are more accurate, with better technique, no wasted movement, and don't telegraph your shots you don't need to hit harder. Silva, Machida and others have shown this, repeatedly, as have many boxers.
If you catch someone not moving with the punch, their own momentum and mass do a lot of the work for you. If you hit someone in the right spot, accurately, you don't need tons of power.
Ngannou probably needs more power, because his skill is inferior, so he needs enough power to overcome not hitting his target cleanly. Fury, with more skill, doesn't need the extra power, because he's much closer to his intended target on a consistent basis.
If I need to hit with X amount of force to KO someone, cold, then hitting it with X + .01% vs X + 150% gives you exactly the same result. Probably a better result than missing the target with X + 150%.
