I think it's simpler. No bundling. You don't have to include a bundle file, you just include files directly as you would have without a bundler. That may seem like a trivial difference, and it could be, but it leads to simpler code and less of a delta between what you think is happening with your modules and what actually happens at runtime.
But Parcel does exactly that. You point parcel at your index.html and it transpiles everything to a dist/ directory including rewritten index.html with imports pointing towards the transpiled files.