Ever try to crush a full Coke can vs. an empty one?
Now I can't say if that's the reason any plane lands that way as opposed to some other, less obvious reason; nor can I say whether it makes any non-negligible difference in a semi-monocoque airliner, but it's true. It's well known that the first generation Atlas rockets had such thin tank walls that they could not stand unsupported while empty, for they'd collapse. They relied on the pressure from the propellants (or tank pressurizarion inert gas) for their structural integrity. They called them "balloon tanks."