No, you are wrong about several things.
First, there is a difference between windproof and waterproof. The windproof jackets can be many times more breathable than the waterproof ones. Waterproof jackets are usually too warm, though 30s and pouring rain might be an exception. Windproof is all you need because you will be wet either way. The main goal of either is to prevent your wet clothing from turning into a swamp cooler in the wind.
Marathon racing conditions are not going to make you put out more heat than shorter races. If you have run in pouring, cold rain before in training, you'll know that marathon pace isn't going to keep you warm. See letsrun's after marathon Huddle interview for a testimonial. With lots of water mixed in at 30-40s F, the conductive/convective heat loss is going to overwhelm the heat that you produce.
With 100% humidity inside, the jacket is not no longer breathable, it's just the opposite. There's more of a gradient pushing the moisture out if it's 100% inside. Though the humidity is also 100% outside. You are going to be wet. It's OK to be wet. You just want that wetness to be warm. Therefore you need a windshell to keep the inside warm by eliminating the convection of the wind and the evaporative cooling effect of wet fabric in the wind. I think what you are trying to say is what I've seen said in many backpacking/hiking sites. They usually say that when the shell wets out, the shell is no longer breathable. That's not quite true either.
I've posted this in one of the other threads, but what would be ideal would be a close-fitting, breathable windbreaker that doesn't flap in the wind (not waterproof) over a long sleeve synthetic shirt. It could be a thinner shirt if you tend to run hot, or a thin mini-fleece shirt if you run cold. The skinny runners could have used something like a Patagonia R1 thickish fleece under a windbreaker. If you try wearing a singlet or short sleeve under a windshell, your arms will be very cold. I know this from experience.
On the legs, you'd also be losing a ton of heat going bare legged. It's easy to see why all the Ethiopian elite men dropped out. But without a shell over the tights, if it's pouring and they are soaked through, you'll get a cooling effect with standard tights. So what you want are tights that have windpanels in front to keep convection from the wind from turning the tights into swamp coolers too. You have many runners who DNFed or slowed substantially because they were close to hypothermic or their leg muscles were too cold, like Huddle or Canaday (what was he thinking taking off the jacket?!! Should have read my advice the night before the race). I'm sure that even Des and Yuki would have been faster if they had worn windfront tights.
Along with that, I'd go with either no gloves, pulling the sleeves over my hands, or ragg wool gloves pulled under the windbreaker sleeves. For the head, a synthetic beanie type hat, and maybe a good, close fitting hood on the windbreaker top over that.
To regulate heat, you can open the zipper, or pull off the hood, or stick you hands out into the cold. If it really warms up, you could take the jacket off and wrap it around your waist, but that would not have been necessary in this particular race.
These suggestions are for pouring rain and 30s and 40s. If it's just light rain/sprinkles, you don't need a windshell. This is from experience. I've run in cold pouring rain, and not just survived, but been comfortable enough that it's not a chore or survival event and would do again the next day. I've also run in t-shirt (synthetic) and shorts in pouring rain at 55 F, and been miserably cold. The skinny dudes (like the African men that dropped out) and women clearly needed more/appropriate clothing.
Citing the build of different runners as a differentiator in this race was accurate, but appropriate clothing would have made it a non-issue. Runners are too often believe that cooler is always better and have a weird, macho thing about running with too little in the cold (witness threads where people say they run in shorts below freezing, or see high school kids wearing t-shirts outside in winter in Alaska). Too cool will hurt performance, just like too hot hurts performance. Most runners skip out runs in pouring cold rain, or don't get that where they live, so they just haven't learned what works.