When performing a build (for production), why does the esbuild.drop option work, but not the esbuild.dropLabels option?

[SimonEast]

I asked a similar question on StackOverflow (https://stackoverflow.com/q/78451880/195835) but perhaps it's worth raising here, also. Here is what I tried adding to my vite.config.js.

export default defineConfig({
  ...
  esbuild: {
    drop: ['console'],     // this line works!
    dropLabels: ['DEV'],   // this one doesn't!
  }
})

For some reason the drop option does what it's supposed to (strips all console.*() calls), but the dropLabels option does not (well the labels get removed, but not the code next to the label). Some responses indicated that this is because esbuild is not used during production builds, but if that's the case, why does the drop option work?

To reproduce this, here's a simple StackBlitz that demonstrates it:
https://stackblitz.com/edit/vitejs-vite-4uczvd?file=src%2Fmain.js,vite.config.js&terminal=dev

(The dev server will run by default, and you can view the console.log's by opening your browser dev tools. To run a production build, quit the dev server with Q, ENTER and then type npm run build && cat dist/assets/index*.js and you will see the production bundle JS output.)