In traditional note-taking systems, the category is the most obvious first-class citizen. In ZK, the little ideas take precedence, because some little idea that belongs to category A can easily end up belonging to other categories B, C, D, ... as time goes on and you study more subjects/discipline.
I'm sure the idea I'm describing is nothing new, groundbreaking, or unique to ZK - but this is the impression that I got, and I've had the pain of having very poorly managed knowledge via Evernote/OneNote/Notion/etc. before. I also dabbled with Anki and mindmapping. I believe the optimal solution is to combine all 3, since mindmaps have the "graph" structure part down; Anki only focuses on recall, but not conceptual understanding/linkage; and traditional notes, while obviously storing more information, are usually organized in hierarchical top-down structures that don't lend themselves well to reviewing or building a deliberate map of knowledge.
Another alternative to mindmaps is something like Jerry's Brain [2], where irrelevant nodes are collapsed until you explore them. Jerry has given extremely compelling presentations because he's used it for something like 20 years.
I am aware of a bias as I write this: I simply might not have had enough discipline when using traditional note-taking systems before, and am going through a bit of a (pre) honeymoon phase with this new ZK stuff. Just my 2 grains of salt.