Question

is it important that rectangle cannot have a volume

Answer 1

Rectangle is a 2 dimensional figure. It cannot have volume. Only 3 dimensional objects can have volume. So it is an important property of rectangle(like all 2D figures) that it cannot have volume.

Answer 2

Recatangle cannot have a volume while cuboid can have volume as it is a 3D figure. Hope it helps and pls mark as the best answer. :)