Not the first time I've heard that.
I haven't done any real work with the doors yet. Mines a 1999 and the rubber gasket that fits around the hinge plate where it extends into the door has dried out and fallen away. It's now a path for water to get inside the door. It drains out the bottom OK, it's just a problem I've not gotten to yet.
When I do get to the doors I'm thinking of rigid foam for insulation. Will have a better idea when I start to work on them.