I suspect that it could be also a rude, uncorrect 'way of saying' from not english speaking forum members.
Couldn't be just a simplification to say that an eink screen is more 'natural' to eyes ?
Is it really just for battery and reading outside that e-ink found his niche?
Maybe as analogic native ;-) i found easier to convince my brain (not my eyes!) that e-ink is paper so a good old book.
So in the end i'm mad and not blind
