I was just doing some thinking, and it dawned on me how easily Kenpachi can cut through just about anything. Here is where the seeds of a new theory were sowed.
If you'll recall, before Ichigo learned Zangetsu's name, he was sort of able to use its abilities, namely Getsuuga Tenshou. Also, Yoruichi stated that Kenpachi's Zanpakuto, like Ichigo's, was in a state of constant release. So, I thought to myself, maybe his ability to cut through basically whatever he hits might be augmented by his insane Reiatsu, like taking a can of aerosol to a lit match to make the fire bigger, but his insane cutting power is his Shikai Ability.
Ready, Set, Discuss!