I agree that discourse does a lot more, but that’s not a problem, even some forum instances use a lot less than what it offers. You just take from the package what you need and discourse can be as basic as a bicycle if you just want to charter, it’s not mandatory to use everything. You can use an IDE as a basic text editor, putting aside its full IDE capabilities (and that’s indeed what I’m doing now, I’m using Rstudio for markdown editing, and besides being a full IDE, it’s blazing fast).
Obsidian falls short by starting with things as basic as opening a mkd document, which it can not do by design. It can’t generate a table of contents of a document, so it’s as comfortable for working as gedit (but gedit at least can open a mkd document!). Not even mentioning that’s not open-source.