ePub may be an open standard, but it has its problems.
https://www.mobileread.com/forums/sho...d.php?t=189866
I understand that people like different things and have different want, etc. I'm certainly not saying that you have to like what Amazon, Google, Apple does all of the time. Buy what is best for your needs. Complaining that Amazon doesn't support epub is like complaining that a Nexus 7 device won't run my iOS apps or I can't play Halo on my wii.