Word > html > KDP?

[Notjohn]

In Amazon's little free book on do-it-yourself publishing, the workflow recommended is to create a Word doc, save it / export it to html, and if there are images, then zip them together with the html file. Upload the result to the KDP publishing platform.

Why? Why in the world does Amazon recommend this? Surely any flaw in the Word doc will simply be replicated in the html. And a Word doc will carry the images with it, unlike the html file, thus avoid that whole archiving routine with its built-in pooh traps.

Sometimes, on the KDP forum, there are complaints about lines appearing on the edges of images in the newer Apple iPad, when an author-publisher uploads a Word doc and the ultimate reader is using Kindle for iPad. I never have experienced this problem, so evidently it's limited to books created and uploaded in Word. Does Amazon recommend the Word>Html route to avoid this, or is there another reason entirely?

Thanks for any enlightenment!

(The book is Building Your Book for Kindle http://amzn.com/B007URVZJ6 )