I'm not disputing the Scabbards of not using Ryou/Haki, but you make it sound like a Wano samurai or any swordsman can only cut with advance haki and that is not true. I just show you the panel Kawamatsu blowing enemies away with a Ryou/Haki attack. Are you going to ignore that???
Also maybe the reason why Kaido didn't get blown away by the scabbards is because they aren't strong enough to do that to Kaido. Just saying.
But there are two advanced armaments. There's barriers and then there's penetration.
Kawamatsu Roger and whitebeard could easily be just using the barriers in those scenes
And then when the scabbards pierce Kaido they are using a modified version of penetration
Look, my point is Oda does not call back to Zoro'a masters exact words wen explaining this if he isn't directly insinuating Zoro used Ryou as early as Alabasta. It's not a coincidence. Especially in this arc where we actually get an entire family tree for Zoro's master making it extremely likely that he knows this advanced armament given his family's origin.
You say the scabbards aren't strong enough to blow Kaido away, Well Oden didn't do that either. Oden who everyone can agree was either comparable to or stronger than Kaido. He also using advanced armament simply cuts Kaido like Zoro using onigiri or something. It's just a cut.
The highest form of advanced armament when used by Swordsmen just makes bigger better cuts. To be able to cut whatever you want and not cut what you don't want is exactly what Hyogoro says is Ryou for swordsmen and it's what Oden and the scabbards do. And it's what Zoro did since Alabasta
Think of it tis way, put yourself in Oda's shoes. Oda went to great lengths to show how ineffective luff is without Ryou. Then he went to great lengths to show how even scabbards that are confer weaker than Zoro can do better damage than luffy simply because they have Ryou.
Now as oda, you've established this mechanic and expect all your readers to understand this mechanic. Then you have Zoro say he wants to cut Kaido. Right after you establish the need for Ryou to cut Kaido. As Oda what would be going through your mind here?
Are you setting up Zoro to go up the roof and get folded like laundry having realised "oh shit, I don't have the haki to cut this guy"?
Or are you setting up Zoro to go up to the roof and cut Kaido with the knowledge that you already told the readers that Zoro should be able to do this given that you made a direct connection to what Hyogoro is teaching luffy and what Zoro's master taught him?
What do you think Oda is setting up for?
And on topic, what exactly about Sanji have you seen compares to either Luffy and Zoro above in terms of set up that justify that Sanji should be able harm Kaido at all?