The plugin ecosystem is what really makes Obsidian different from the rest.

While OSS is nice, in theory it allows vibe-coding personalizations, without a clear plugin standard then every update would cause a merge headache.

And there is no lack of text editors.

The first real Obsidian alternative would allow use of existing Obsidian plugins. And I think this one thing could really make an alternative gain traction, with both users and those who contribute to the plugin ecosystem.