Let's say we had no need for babel or similar level transpilers. There would still be benefit to webpack-like bundlers, if for no other reason then for perform

Let's say we had no need for babel or similar level transpilers. There would still be benefit to webpack-like bundlers, if for no other reason then for performance/obfuscation reasons we would probably want the number of modules as seen by the broswer to be smaller than the number of modules that developers like to use for development purposes. Many would still want minification for both performance and obfuscation reasons. Many would still want to tree shake out any unused code from the libraries used (again for performance reasons). Once one have all of that tooling, adding a babel like transpiler to the stack is not that big a deal.