OK, someone died. You made an incorrect statement (that they would have died from a seasonal flu anyway. Swine flu is more likely to affect the healthy.) about their death to further an agenda you have. Fine.

I think I may be using "linguistic prescriptivism" in a slightly different, more general sense than you have in mind.

Yes, and one completely disconnected from the actual practice of the thing.

People always try to distinguish themselves as social superiors, it's what we (including linguistically-educated people quick to jump in with cries of "there's no so thing as "correct" English usage! Language is fluid!") do. People also try to get others to share their views about art, music, and morality, and tend to like more those who do so. I fail to see what the problem with that is. The only difference is that the issue of morality has tended to get wrapped up with the power of the state, so views on that one have more consequences (not to say that issues of language and culture don't have significant sociological implications).

No, there are more differences here. In your comparison here, language falls somewhere in between art/music and morality. People are far, far more likely to assume a gustibus non disputandum attitude about art and music than about language. If you don't like a certain form of music, you might get called tasteless or a philistine at worse. If you speak a non-standard dialect, on the other hand, you will have people say that you are illogical and mentally deficient, or even worse. Especially if dialect in question is AAVE; inner-city black children have been matter-of-factly said to not have language at all in some academic circles.

In any case, if I find one form of the English language more aesthetically pleasing than another, why shouldn't I prefer that it become dominant?

You can prefer all you want. The problem starts when you bully other, less educated people than yourself into bowing to your preferences as superior for spurious reasons--which is what actually happens in practice.

However, the gap between is and ought remains as wide as it ever was, and my reasons for preferring certain forms of English are mainly based on aesthetics and tribalism, not some imagined sense of the practical superiority of one form over another (with the vehement exception of the Oxford comma).

But you see, "cuz I say so" is a pretty bad reason to demand that other people talk and write in the way you say they should. It's one virtue is that it is at least honest--a typical prescriptivist will cover it up with piles and piles of bullshit about "logic" and "aesthetics" and "clarity" and "avoidance of ambiguity" and on and on and on.

Every death caused by car fires is absolutely, 100%, cheaply preventable. All that's needed is a racing-style fuel cell, which contains a flexible bladder inside that prevents fuel from spilling when the hard outer shell is breached (that's why fires in racing are basically a thing of the past these days). These are commonly used in racing, and are standard equipment on many aircraft. They require no extra maintenance and the additional cost would be negligible in mass production. The only downsides are a very slight increase in weight (maybe 10lbs) and decrease in capacity (maybe a liter or two on an average-sized car tank). It's literally a tragedy that this is not required on all cars. It's much more important than curtain airbags or fucking OnStar. It really pisses me off when I hear of someone burning to death in a car accident.

hat does that have to do with the lack of development for anything other than Windows?

Lack of development? There is development happening for OS X and Linux. It's just not ready for end-users yet.

What does Mozilla's head start have to do with the fact that they are apparently able to do cross-platform development better than a company who has vastly more people and money at their disposal?

Because development isn't simply a matter of money. It takes time to develop software, and organisational/human/communication factors impose an upper limit on how fast development can move. Mozilla have a codebase where 15 years have been spent in development. No amount of money can compensate for that head-start. Mozilla aren't developing any faster than Google, they are further ahead because they've been doing it longer.

Even the original releases of Netscape were cross-platform

The original releases of Netscape were far, far simpler products. I could write "Hello, World" in 30 seconds that would run on more platforms than Chrome - does that make me better than Google? No, because the task of writing a modern web browser is substantially greater than writing "Hello, World" - and substantially greater than writing an early 90s web browser.

So basically even at the start when they had even less resources they were somehow able to do better cross-platform development than a multibillion dollar, multinational company.

Yes, because they had less to do. If your codebase is a fraction of the size and has only a handful of features, of course it's easier to port it to other systems. By the way, have you tried running those early Netscape versions on Linux and OS X?