That's called third hand information. You're allowed to subscribe to it, but unless you have done it yourself and can vouch for it, then stop pushing your ideas on us and telling us we're wrong.
I'll help you out. The AR on the underside stops the polished dial from reflecting light off the dial surface, then back to the underside of the crystal, then back to the surface of the dial, etc... it's like light caught between two mirrored surfaces reflecting back and forth. If you put AR under the crystal, then it will diminish and inhibit the back and forth, therefore the dial looks sharper. AR on the top tends to make the crystal more transparent, but only looks absent in the presence of the underside AR as well.
The other factor in all this that could be affecting the sharpness of the dial when compared to gen is the dial itself. If the polish is too high on the dial, it can cause more reflection. If the small angles of the hour markers or hands are just right, they can also reflect more light onto the bottom side of the crystal, moreso than the gen does if it has angles that deflect the light laterally rather than vertically. All of this plays into how legible and sharp the dial looks. To say that the AR is the only factor is just one factor. Of course it's the most influential factor, but it can be compromised by other reflective surfaces that do not match the gen in either polish or geometry. Imagine looking out a window with AR at noon vs. 5PM when the sun is lower and the angle of attack has changed. It's easier to see out of the window at noon, no?
Many factors com into play here, so on this one "flaw" as you call it, I'm showing you that you are only taking one factor into consideration; that being the AR of the gen vs the rep. They may in fact be the same, they may not. But there are other parts under that AR that play vital roles as well.
Critical thinking.
