A
We know that the best haki user are not DF user , best exampe Roger , Garp , Rayleigh , Mihawk and Shanks
so i assume the main reason for that is that having a hax DF have a major draw back for the user as well
those people who have such DF can win most their fights without the need to use haki , and as Rayleigh said
haki blooms in extreme fights , sure there is still a possibility of growing but only if they fight someone with equal hax DF or much better haki . but such person are rare.
for example Akainu vs Aokiji they fought 10 days i imagine now they have better haki then they had in MF
Magellan for example i think he has really weak haki , because he win his fights with one strike usually
I imagine Kaido doesn't have the best armament because he already have a tough body and a DF that make his body tougher
that goes for Kizaru i think he doesn't have the best armament either because he is faster and is logia but at the end an old Rayleigh went with toe to toe
Buggy will not have a good armament since he doesn't have to defend himself against swords.
Blackbeard will not have better armament than shanks because he has the gura gura no mi
Sabo will be more powerful with mera mera no mi because he has good haki before he ate it .
even Zoro seemed to have better armament than Luffy as they just entered the new world because Luffy's DF make him strong enough for the time being now after he had to fight people like Katakuri and Kaido he improved his haki.
so Law doesn't have a good haki because of his hax DF as well i bet he never has such difficulties before he fought Doffy
so i assume the main reason for that is that having a hax DF have a major draw back for the user as well
those people who have such DF can win most their fights without the need to use haki , and as Rayleigh said
haki blooms in extreme fights , sure there is still a possibility of growing but only if they fight someone with equal hax DF or much better haki . but such person are rare.
for example Akainu vs Aokiji they fought 10 days i imagine now they have better haki then they had in MF
Magellan for example i think he has really weak haki , because he win his fights with one strike usually
I imagine Kaido doesn't have the best armament because he already have a tough body and a DF that make his body tougher
that goes for Kizaru i think he doesn't have the best armament either because he is faster and is logia but at the end an old Rayleigh went with toe to toe
Buggy will not have a good armament since he doesn't have to defend himself against swords.
Blackbeard will not have better armament than shanks because he has the gura gura no mi
Sabo will be more powerful with mera mera no mi because he has good haki before he ate it .
even Zoro seemed to have better armament than Luffy as they just entered the new world because Luffy's DF make him strong enough for the time being now after he had to fight people like Katakuri and Kaido he improved his haki.
so Law doesn't have a good haki because of his hax DF as well i bet he never has such difficulties before he fought Doffy