Knowing Kishi's fetish for inserting symbolism in his manga, this completely makes sense.The Tsuna is a type of rope. The word Yokozuna means horizontal rope because the Yokozuna wears it during special ceremonies. Thats why Orochimaru wears, it because he's into sacrifices, ceremonies, and rituals. Sasuke wears it because he was Orochimaru's pupil.
You must be registered for see images
It's not like this is the only unrealistic thing in this Manga to begin with.To be honest i dont see how that rope would be able hold his sword sheathe. VERY UNREALISTIC MANGA WTF.