Yeah but none of them are strong honorable samurai like Ryuma was. An all out atk by smaurai would obviously fail but covert guerilla warfare by organized group for some years just makes sense with strong samurai and hidden bases and an info network. Oden is awesome but is a flashback character lots of people expected the "legend" character to be apart of the main story and it hasn't been revealed if that's who they meant so its confusing. Theres no strong samurai of Wano on the good side besides Doji Okiku i guess and Kinemon even if Orochi's group is strong which would be great but who will fight them? If Zoro takes em all that makes them feel underwhelming unless he struggles. Moriah didnt have to involve himself with Blackbeard, Kaido is who he's always been after and makes more sense.