Its over ZKKboys. Roger wasn't WGS same way Shanks isn't WGS.
I knew Shanks and Roger would have similar styles. Not once I see you saying Shanks can use Kamusari.
Never said Shanks couldn't use Kamusari either, I simply made no assumptions at all about Shanks techniques. Roger wasn't called WSS but so wasn't any other powerful
swordsman "sword user" in his era, simply because that information wasn't relevant to the narrative. The most relevant title is the PK title, while the WSS title is tied to Zoro's dream, so there is no need for Oda to elaborate the WSS of the old era, prior to the great era of piracy.
And how exactly does Kamusari, an advanced technique performed with great swordskill by a supreme grade blade disprove Shanks' standing as a swordsman?