In Amonkhet, there were a lot of things that used that exact wording when checking for deserts as a conditional statement. I wanted a third conditional statement, and that was the one I happened to choose.
Granted, an argument could be made that it would already have had three, because the City's Blessing requires both "something with Ascend" and "ten permanents" and that card does not in itself have Ascend. Still, I felt like including a third official requirement, and the "desert" thing is what I settled on.