Well, it has a bunch of plugins for making your notes folder into a database, or cataloguing meta data, or adding graphs, spreadsheets, mind maps, or flow charts, but I don’t really use any of those.

The only thing I use is the Mathjax plug-in for keeping notes about interesting publications.

Aside from its plugins, Obsidian is a great markdown editor and has a folder view and search integrated. I like it for that. My alternative is Apple notes, but long notes are hard to read there, so having markdown view is a positive experience.

If your editor has a wiki mode (like Emacs' org mode) then maybe nothing. If not, then Obsidian is your browser and your editor is your editor. For example, git syncing between Android and desktop isn't working well for me, so I edit directly in github UI and browse in Obsidian. The fact that Obsidian works exactly like that is one of the biggest benefits of Obsidian.

The integration of notes and tasks - that’s unbeatable. While I journal stuff during the day adding tasks is one macro away, and these task can then be searched easily. Your journaling becomes a database of stuff to do.

I feel like the only reason I use Obsidian is because of the "real time" markdown editor. If I could have this in Zed (not split view between source and render) I would probably not used Obsidian anymore.