Starting July 2018, all iOS app updates submitted to the App Store must be built with the iOS 11 SDK and must support the Super Retina display of iPhone X.
Developers can get more information from the usual place.
I realize it's a pain in the ass for developers to keep updating their apps to support device changes like the iPhone X display. Design is hard work and yet customers don't see it as valuable enough to pay for.
And, yeah, it's ironic that device fragmentation was something iPhone developers used to poke fun at Android for, and now we have multiple phone and tablet sizes to support in iOS as well. Nowhere nearly as many nor as random-seeming, but enough for it to require AutoLayout, size classes, and thinking about how apps scale.
Indie developers are usually quick to jump on these changes regardless. Corporate apps, not so much. And, even though it's work for developers, it's better for customers, and that's the important thing.