Why not build skills and an MCP for markdown or obsidian? I'm using both at present and it's fine, bit would like to understand the differentiating factor here.

Example of the functionality that's OK specific: we made it so that e.g. Claude Desktop (or Codex, Cursor) can open the OpenKnowledge web viewer within their own embedded web viewers, to make for better side-by-side editing. Since Obsidian is closed source, we wouldn't be able to make that work.

Making the skills/MCP specific to OpenKnowledge allows us to optimize experiences like that.