If you've invested time into adding metadata and app-specific markdown to your setup, you lose that when you move to another tool. Has happened to me before. It's about vendor lock-in when you go too deep into their ecosystem.

And instead of open text files with plaintext properties in the YAML frontmatter standard, you want to do.... what, exactly?

And the plugins are all OSS, on GitHub.

What do you imagine is more open with less lock-in?