It's not really comparable. The X didn't strive to achieve a new, ultra thin form factor with the same or improved tech as the previous generation. It was all about a full screen display more than anything else, which isn't remotely as difficult to implement whilst keeping on adding more tech.My comment that you are replying to was making a point on how the Air cannot be compared to what the X did. The X made advances over the 7 and 8 while virtually not losing anything, then achieving the form factor that it had. The only thing that people could complain about was losing TouchID to FaceID. Remember the X was released along with the 8 in the same year.
Whilst the Air is the reverse, Apple had to shave away features for it to become this thin. Even if it only lose one feature it is already backwards, and we are able to make a list.
The Air has a few compromises, granted. But they are just so minuscule in comparison to what they have achieved with the overall form factor. I would totally understand if the device was woefully underpowered with a previous generation A-series chip or if it had significantly less RAM or something. But really, a telephoto camera, a GPU core and a shoddy built in speaker? I just don't get it.