Should babelHelpers be `runtime` ?

In [rollup's documentation](https://github.com/rollup/plugins/tree/master/packages/babel#babelhelpers), there the following excerpt:

> 'runtime' - you should use this especially when building libraries with Rollup. It has to be used in combination with @babel/plugin-transform-runtime and you should also specify @babel/runtime as dependency of your package. Don't forget to tell Rollup to treat the helpers imported from within the @babel/runtime module as external dependencies when bundling for cjs & es formats. This can be accomplished via regex (external: [/@babel\/runtime/]) or a function (external: id => id.includes('@babel/runtime')). It's important to not only specify external: ['@babel/runtime'] since the helpers are imported from nested paths (e.g @babel/runtime/helpers/get) and Rollup will only exclude modules that match strings exactly.

I've noticed `microbundle` uses `bundled` option... is there any way to change/configure this? And should `microbundle` use `runtime` by default, given that it focuses in library bundling?