Because getting a high resolution, oled, good aspect ratio, fast refresh rate display is much easier and more affordable on a tablet? Sure, even with a kickstand it is not quite as "lapable", but the screens are nice.
On a related note, when is pkvm supposed to be available outside pixel devices? Getting a proper linux or windows VM on one of the bigger samsung tablets + keyboard just might replace my laptop (yeah, remote stuff works, but offline on device would be much more convenient, e.g. on trains).
What seems crazy to me seems to work for others. I assume many of them are constrained by what they can afford.