I think that's a fair point. I've also read some stuff about how, when the two previous Kim's died, they split up their positions and diffused power. So, when Kim Il Sung died, he was President, which made him Head of State, Head of Government, and Commander in Chief, but they then made those three roles into separate offices, which is why he's the "Eternal President", because he's the only president.

I don't have anything to back this up, it's just a hunch and academic studies on the internal complexities of dprk politics are incredibly rare in the English language, but I get the impression that there's a line struggle around the personality cult, with with certain cleavages wanting to diffuse that power, and others wanting to reinforce it.

Even more of a hunch, so take this with an even bigger grain of salt, but I also suspect it's possible that this might stem from the historic influence of anarchism in Korea. Lots of Korean anarchists went on to defect to the DPRK, and some even became pretty high ranking officials. That said, I couldn't tell you if that influence is still there, this many decades on.