It’s a non-starter for me because I sync my notes, and sometimes a subset of my notes, to multiple devices and multiple programs. For instance, I might use Obsidian, Vim and tasks.md to access the same repository, with all the documents synced between my desktop and server, and a subset synced to my phone. I also have various scripts to capture data from other sources and write it out as markdown files. Trying to sync all of this to a database that is then further synced around seems overly complicated to say the least, and would basically just be using Trillium as a file store, which I’ve already got.
I’ve also be burnt by various export/import systems either losing information or storing it in a incompatible way.