They look cool, but it is known that they don't add much.

In Obsidian, the local graph has real uses, but the global one is mostly to see structure in your notes and look cool on social media.

I was researching and prototyping a graph like Obsidian's before Obsidian came out, based on the ideas in "how to take smart notes"

https://www.youtube.com/watch?v=a6yUA46ek6M

I believe the direction of UI I was exploring there has more than what graphs currently have, although I didn't have the time to build it out and I saw that the site has been offline for a while.

It was a working tool though.