I'm the third owner of an LL bean coat, the first two owners being my older cousin and older sister. I've replaced the zipper once in the 15ish years I've had it but the rest of the coat is still in perfect shape.

The point is that it's staying in a smaller area so it can drain slowly into the ground, instead of running off parched hydrophobic soil to a far away spot. It restores groundwater locally by slowing the drainage and allowing plants to grow there.

It's also not illegal to collect rainwater in many places there's just limits as to how much you can collect and store at once.