I think you must have missed that the first post is a replacement of the actual feature request that someone submitted. I have no dog in this fight, but it's pretty slimy to respond to someone's request by overwriting it with your explanation. They effectively hijacked the requester's name, profile picture, and who knows how many upvotes to push their own message instead of letting them have their say and, you know, replying.

Which one, the go ahead and "define your own custom loader"? You mean re-implement the image export that is sitting right there in their express server... from scratch? Hah.

NextJS won't let you export their optimized images in a static site export because they want _everything_ running through their Express server.

Why's that great for them? Because they get to charge you for image bandwidth and image optimization. This is called vendor lock in.

Sources:

In vivo (v13.3.0):

  > npx next export
  <...>
  error - Image Optimization using the default loader is not compatible with export.
    Possible solutions:
      - Use `next start` to run a server, which includes the Image Optimization API.
      - Configure `images.unoptimized = true` in `next.config.js` to disable the Image Optimization API.
    Read more: https://nextjs.org/docs/messages/export-image-api

and https://vercel.com/changelog/changes-to-vercel-image-optimiz...

> It reminds me of the npm hate

The comparison to npm is worrisome. npm inc. spent years trying to make a profit & grow beyond "privately owned package registry". It failed and was acqui-hired by Github back in 2020 for an amount far beneath its capitalization.