What you are witnessing is technology 50 years ago, a time when trucks were glorified workhorses not some sissy thing you drove to the country club. That rubber strip is an anti-rattle device and the holes are what's kept the bottoms of the doors from rusting through all these years. Water isn't so much the problem as water that doesn't evaporate in a reasonable amount of time.
Unfortunately, they didn't consider that rubber seal at the bottom which has held water against the inner panel and caused that to rust.
So, one win and one loss. Such is the joy of owning an old vehicle.
