I've never understood the draw of Obsidian. Their website makes it seem like the "graph view" is their big differentiator, but why is that useful? Why is it useful to know how various topics are vaguely related, and view a giant web of it? Or is their marketing just confusing me.. and really it's just a markdown editor with linking?

Linking is a big thing in knowledge-managment. There is a new hype weaving around ATM to rediscover functionality which exists in old tools for decades already. Graph-View pokes in that area. Similar reasoning for the tag-view and search.

But Obsidian has more points speaking for it. It works on local files/folders with well known types. No special formats involved which lock you in. Recently it started development of it's plugin-API which already started gaining some useful plugins from the community. And overall it's quite polished and userfriendly, not many quirks and corners which stay in the users way.

Graph view sounds ideal Zettelkasten but in practice the graph becomes chaos once you get to a certain number of notes. It's more useful to have a local view of a notes' links and backlinks, like https://traverse.link/ does

there’s a style of note taking called zettelkasten, recently popularized by a service called Roam Research, that is ALL ABOUT linking notes together and traversing the note graph. obsidian is targeted at that use case.