Author here: I use mermaid lot as well and for some things like process flows, and to model interactions it it outrules excalidraw and posts will follow where i need exactly that. but to visualize things high level i find excalidraw way nicer.

I made it so that anyone who writes mermaid in HN comments, can see it inline comments, when the OJ extension is installed.

https://oj-hn.com/assets/mermaid-light.png

You know you can just paste mermaid into excalidraw?

It has a mermaid WYSIWYG editor and once the diagram is inserted you can edit it, move objects, add text just like you had drawn it directly in excalidraw.

I usually enter mermaid and then move things around to my liking rather than drawing from scratch.

You can also paste csv in, it's been a while since I've done it but I think it even generates a chart.

Mermaid is awesome, since it has broad support, can be committed to repos, and can be created and edited very easily by LLMs.