Is sync really the reason?
I'm curious if you have considered the fact that reading from a kindle e-ink screen is infinitely better than reading of an LCD/LED screen, regardless of the resolution.
The e-ink makes for a far superior experience than the Apple, Android or other handheld or tablet devices.
This, I think, is the crux of the 60:1 ratio cited by the author in your article.
Would like to hear your thoughts on that perspective.