The killer feature of Obsidian was the wikilinks, but now that other editors are getting that feature it is replaceable.
But the other killer feature is avoiding vendor lock-in. With some apps your notes are on their servers in an inscrutable data format, and some apps don't even let you export without paying. With markdown notes on the other hand you can take your notes anywhere, sync them with git, dropbox, syncthing, etc.
You're not bound to obsidian, and your markdown notes format will always be readable, unlike many of today's formats! See [1] "LibreOffice is better at reading old Word files than Word"