How would you attach images to your notes and manage them in a git repo? How would you encrypt your notes?
How do you insert current or tomorrow's date in a note? How do you find all the notes tagged with a date? ¹
Most importantly, what would you do when you accumulate several thousand notes, and suddenly Obsidian authors ask you to pay for it?
Having my note taking system in Emacs has incredible benefits - I have google-translate, thesaurus, dictionary, spell-checker, Grammarly checker, etc., All right here, everything is accessible without focus and context switching. And, of course, I can change virtually any behavior of any part of the system. And I never have to worry that someday, someone would ask me to pay for "premium features".
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¹ I don't know, perhaps Obsidian has some of those features, and maybe they are even better and more intuitive than in Emacs, but I doubt it would ever be as versatile.