Verbal communication may be the default option but there is a reason we often defer to (carefully constructed) written communication in complex domains. While emotional nuances may be clearer (to some) in verbal communication, the details of complex ideas often are not. Have you ever tried to "talk code" at someone without the aid of written code? It's woefully inefficient and prone to miscommunication. Writing allows you to externalize state and forces you to make explicit unstated assumptions that may simply go uncommunicated in verbal exchanges. Indeed, in your examples, the screen share on which the code can be read by both parties seems to be doing most of the clarifying work, that is, you are cheating and using written communication anyway.
>I said most people learn to speak before they learn to write. Is that untrue?
This is true but completely irrelevant. Most people also learn how to dance before they learn how to write, that does not mean interpretive dance is a suitable medium for conveying technical information.
>How about the idea that you can communicate (crudely, sure) with gestures even with people you don't share a common language with?
This is an edge case, and again, kind of cheating as you are attributing the benefits of visual aids to the verbal format. It does not provide any evidence that spoken communication is universally better.
>How about the idea that both writing comprehensively and reading comprehension are high level skills that many people don't possess enough to truly communicate effectively via writing? Do you disagree?
Reading comprehension and the ability to write cogently are basic skills of any knowledge work. I think people who are poor communicators are probably poor communicators regardless of medium, so this is a red herring. In general, the things you are saying are true to some extent but do not constitute an argument for verbal communication being universally better than written (your claim). Rather, even if I am charitable and ignore the clearly fallacious parts of your argument, at most you've shown that in some circumstances verbal communication has some advantages (a much weaker claim which does indeed seem rather uncontroversial).
>I don't think it's unfair to say that verbal communication is a cornerstone of the (near) universal human experience.
>This isn't just "my preference" is what I'm getting at. I'm pretty sure it's just the human default.
So, those of us with hearing problems or speech impediments are simply inhuman? This is the arrogance I was talking about. Your assumption that your preferences and the way that you work most efficiently is universal when it is clearly not. Again, you are free to conduct yourself in this fashion but it won't make you many friends.