And if your database got corrupted, you would lose everything. Or everything not archived. And being a proprietary database format, if Notion tanked without warning, you could not open that data anywhere else.

All of the information in Obsidian is stored in discrete files that can be opened with any text editor or word processor. If you lose one file, you lose one file. Not everything in the database. And if the makers of Obsidian stop development or Obsidian breaks, you can still access all of those files.