[giorgioz]

I think tree-shaking will be a default in new JS bundler. ESbuild seem to enable it by default: https://esbuild.github.io/

I think the reason some other bundlers like webpack didn't/don't have it by default is because tree-shaking became popular after they were invented and tree-shaking was added to the bundler later on as an extra nice-to-have feature.

It seems webpack has built-in support for tree-shaking from version 2. Latest version of webpack might have it enabled by default (not 100% sure but possible) https://webpack.js.org/guides/tree-shaking/