Love the respect for privacy that Obsidian brings. No tackers and no shit. It's beautiful to find such a great app with a respect for something so important.
It's still a proprietary and closed source application, so you can't be sure what it's actually doing. You can monitor which files it accesses and the network traffic it generates, but you can only trust that they're respecting your privacy according to their policy.
It seems like a great program; it embraces open formats and is very extensible. But I don't think privacy should be a reason to use it while it's closed source.