Bleach's swordsmanship isn't something spoonfed to you in order to understand, it has legitimate swordsmanship from real world and fictional practices. Learning how to wield a Zanpakuto and unlocking new moves with it aren't pure hax feats. Getsuga Tenshou is literally a Zanjutsu technique, hence why Isshin could use it. Mastering Bankai is a skill that only very dedicated, talented, and experienced individuals can achieve, hence why it is one of the standards for being a captain, aside from defeating them (which Kenpachi did btw against another Kenpachi, whom are potrayed to be the most skilled aside from Yamaji himself)
Plus, naming moves doesn't equate to skill, if that was the case, Mihawk would be the most unskilled swordsman in fiction, and we know Mihawk skillstomps every KnY character effortlessly.
Just having hax isn't good enough as a Shinigami, it's considered shameful for one to not know Zanjutsu.
Bleach swordsmen have also shown better feats too, like Ichigo deflecting omnidirectional paper thin danmaku (which people claim is only a speed feat despite the fact that Ichigo clearly had trouble keeping up even in Bankai, and that you need ridiculous dexterity to perform such a feat), or when Ichigo outskilled Ginjo and took advantage of his sword's slow swing and the surface area of his sword by turning it on its axis to split his sword in two, or when Ichigo mastered dual wielding instantaneously and fought Yhwach. Those are feats that no one in Kimetsu has done, or probably could ever do, and that's just the ones I have easily on hand. To pull out the simplest argument: Unohana mastered 8000 different sword styles, and Yamamoto massively scales above her.
Just because you rely more on swordsmanship for the overall power system, doesn't mean you have better swordsmanship than others that don't, again, if that were the case, KnY characters would be contending with characters like Zoro since OP's main thing is Haki, and we know that is sure as hell not happening. Plus, Shinigami rely on it only slightly less than the Demon Slayers, only due to the fact that they have other shit like Kido.