Yes, that works when you have a compilation step on the server.

But it would be nicer to have a complete project in the browser.

Think of it this way: When someone hits 'export' and downloads the zip - how will they be able to run what they built? They need to set up a whole serverside toolchain. If you instead load vue clientside, the downloaded thing would work right away. Without any setup or dependencies.

This applies to the React example just as well.

The server side toolchain is how most devs do it these days. I personally prefer to skip it.