I don't think you realize how ridiculous and complicated this all sounds.
I mean the second game opens with some kind of matrix like plot where the main character was sleeping for two years in a computer version of the real world, and you haven't begun to address anything else. As the kids would say, erhem, This shit is whack.
Well, yes, overall there are some whacky shit in KH. My point was that the ideas of Heartless & Nobodies are not complicated nor do they, as concepts, ruin the established lore of KH, which is what the post I was answering was claiming. Think of it crazy (and it kinda is, but there's nothing wrong with crazy ideas like KH's), but complicated it isn't. At all. Plenty of other fantastical fiction where people lose their souls and leave behind empty husks of bodies that might still maintain some level of functionality. Nobodies are really just a fairly natural continuation from the existence of the Heartless. Like, if we accept that a fantastical, cartoony universe like the one in KH1 exists in the game and that it has the Heartless, which are poltergeist-like entities created by darkness consuming people, we can ask what happens to the empty bodies left behind, then? Not a bad or illogical question to ask or explore in a story, really. Not saying KH does the exploring well, but all in all on an idea level KH can be quite fun if you don't let a bit of crazy ruin your fun. The existence of Heartless is already crazy, that there is also a body left behind is crazy too but kind of logical continuation of the Heartless concept.
And Kingdom Hearts with all its ideas makes a lot more sense (in a way) after you acknowledge how much Disney properties affect & are mirrored in a lot of KH concepts. You say KHII's beginning is some "crazy Matrix shit", but KHII also has a Tron world. So if the universe of KH can have a world inside a computer with Tron, it can have that outside of Tron as well. Similarly Pinoccio is a puppet who grows a heart, so why can't other empty husks grow hearts as well? The concepts are very Disney-like. Like, a lot of Disney Movies have crazy storylines ("some people in the world can turn humans into monstrous animals who then have limited time to learn to be better people before the last flower petal falls out of a rose and they have to remain forever a beast" is an insane concept, Pinoccio basically sounds like KH with its puppet that grows a consience and becomes a real boy). KH just kind of mixes & matches many of those concepts in small & big parts into a single continuous story, so it gets a bit busy. It's the execution that mostly falters, but on an idea level KH isn't as incomprehensible as you people claim. Crazy yes but a bit of crazy in a story never killed anyone.
But yeah, how is "body succumbs to darkness, creates an evil spirit and leaves behind an empty body" complicated?