Categorizing ideas (and or indexing them for search) can be useful for quick bulk storage, but the additional work of linking ideas to each other with in a Luhmann-esque zettelkasten can be more useful in the long term in developing ideas.

Storage by category means that ideas aren't immediately developed explicitly, but it means that that work is pushed until some later time at which the connections must be made to turn them into longer works (articles, papers, essays, books, etc.)