Surely any sane person vibe coding a note taking app just has it save all the notes as markdown files to disk? At that point making a backup is trivial and they're unlikely to get corrupted.
As stated in my first comment, Obsidian does not support Emacs keybindings properly, nor is it open source. Writing an extension to add Emacs keybindings is not at all trivial, because you have to work around a lot of existing and undocumented functionality.
There are other reasons for not vibe coding your own alternative, but as LLMs keep progressing, these reasons may become less relevant.