Concepts are just densely linked ideas
The idea of a concept is just a densely linked network of smaller ideas. They were put together by someone at some time, but all information and knowledge management works this way, in a modular way at first coming together to create a concept.
Ex: Evernote style note-taking -> Flat file system like NValt -> Drafts (just capture) -> Zettelkasten/Cards/Concepts/Obsidian (PKM)
One could also argue that the emergence of Markdown was part of that journey too.
Source: Peepnbrick, How to Achieve More While Studying Less
Related: nick milo, linking your thinking. how to take smart notes, Notetaking, notemaking, idea generation, concept formation
Another idea: Idea Generation vs. Concept Formation