> The features of LSP are exactly the features of VS Code. So if you create a different editor, it will only support what VS Code does.

This is not true since LSPs can add extensions to the existing API. For example: https://github.com/rust-lang/rust-analyzer/blob/master/docs/...

> If you create an LSP, it will work best in VS Code.

Any editor can work just as well as (or even better than) VS Code.