> In which way does Obsidian "create value and extract structure and knowledge from your Markdown files"?
It's search is extremely fast, plus with a bit of metadata, you can pack tons of information into a standard markdown file.
Moreover, when you start to add more and more knowledge, you start to connect notes to each other, which creates a Zettelkasten-like connected notes web. I write gigantic notes generally, but even they have connections, and again the searching for linking is so instant, you can write at the speed of thought.
I have a simple tree note organization scheme, and Obsidian can handle it extremely well, plus files are open on the filesystem. I can unleash another tool on top of that file tree, if I want to edit or analyze them.
I still use Evernote for some personal notes, and Joplin is just the same thing, and its limitations on file/note organization is very limiting for my needs.
Lastly, Obsidian vaults are completely isolated from each other, so the vault which I manage my small digital garden is completely isolated from my work vault. They are on different places, sycned differently, can have different plugins, etc. This is a very nice feature.
TL;DR: Obsidian is a pure "knowledge/documentation" management tool and allows for creation at the speed of thought. It's unobtrusive and Markdown metadata is extremely powerful. Also leveraging internote-connections supercharges Obsidian.