[paulhodge]

This comparison done by Google is really helpful at understanding all the work that Webpack (and related tools) do: https://bundlers.tooling.report/ .

Click through each test and read through some of the descriptions. They do a lot of advanced techniques that are important for web performance.

Those optimizations are another big part of why modern Javascript build tools are so complicated. There's no other language where we care nearly as much about optimizing for code delivery. On the web, a frontend app should (hopefully) be around 100k of Javascript bytes, and it should have good caching and CDN behavior. Compared to other platforms where 10mb to 100mb binaries are considered just fine.