How does macOS relate to iPhone X? Thats where you are losing me. Shouldn't you be saying they should have waited until X to launch iOS 11?
Historically, Apple has released macOS (OS X) and iOS updates at the same time... ostensibly because of shared features... and those releases have been released in conjunction with the new iPhone launch. I am saying that it's all different this year because Apple is more focused on the iPhone X instead of the 8/8+.