This works for me. So long as you have a Kindle device registered on Amazon, you should be able to download directly to a desktop. The DeDRM plugin mentioned removes the DRM during ingestion into Calibre and requires an actual token from Amazon which is linked to the Kindle device you downloaded from.
I use this to get Amazon eBooks into my Remarkable 2 which requires DRM free.
The post isn’t claiming perfection. It’s claiming production ready. Very different things.
The confusion there is the claim that good/perfect means done. It means ready for use and extensible.
Note: I’m not agreeing/disagreeing with the claim. Just clarifying the point