Perhaps you misread my comment
I did not, but you misread mine.
Haki and swordsmanship have the same relation as brawling and haki.
Haki is not some exclusive power system for a specific fighting style. Haki is used by ANYONE. Be it DF user, swordsman, brawler or clown.
You can not become a strong swordsman without haki, much less the strongest. Haki will always remain as the filter.
Swordsmanship, or using a weapon in general, has very real perks even in One Piece.
A fighting style that incorporates a weapon or a fruit will be inherently stronger for several reasons.
Its easier to avoid attacks. If you can block with a weapon, especially against another sharp or pointy one, it requires no haki to do so. Someone unarmed has to use haki and therefor stamina.
Its easier to cut something in half than punch it in half. It requires less energy.
The big downside is that losing the weapon can be devastating.
In the end haki could even the field. Which is actually pretty stupid if you think about it as it invalidates nearly all fighting styles.
This is still up for debate though. We only had one unarmed alledged top tier so far, Garp. Having literal magical powers on top of prime haki would still leave a DF user at an advantage.
When haki is the only deciding factor in a fight then why are there even different fighting styles?!?
So I would not exactly rule out that swordsmanship in itself was a deciding factor why Roger was Whitebeards equal. It was not his haki alone that that it, it was both. Rogers swordsmenship together with his haki.