Nitpick: "caliber" has several different meanings, all of which (confusingly) relate to a gun's barrel dimensions. The one you're using is a measure of internal barrel diameter, essentially a shorthand for inches (i.e. .22 caliber); the decimal point often gets dropped in that context, though. It's equally correct to speak of caliber in terms of some other unit, like millimeters. When you're talking about large weapons, though, the word means the length of the weapon's barrel as a multiple of its internal diameter; a tank gun might be 120 mm 55 caliber, making it 6.6 meters long.
The American customary system doesn't as far as I know have a general-use length unit in the millimeter range. There are a couple of typographical) units) defined in terms of the customary system, but they haven't really escaped into the wild.
Please don't use URL shorteners. I want to upvote this for informativeness but aagh...
Today my coworker Marcello pointed out to me an interesting anti-majoritarian effect. There are three major interpretations of probability: the "subjective" view of probabilities as measuring the uncertainty of agents, the "propensity" view of probabilities as chances inherent within objects, and the "frequentist" view of probabilities as the limiting value of long-run frequencies. I was remarking on how odd it was that frequentism, the predominant view in mainstream statistics, is the worst of the three major alternatives (in my view, you have to presume either uncertainty or propensity in order to talk about the limiting frequency of events that have not yet happened).
And Marcello said something along the lines of, "Well, of course. If anything were worse than frequentism, it wouldn't be there." I said, "What?" And Marcello said, "Like the saying that Mac users have, 'If Macs really were worse than Windows PCs, no one would use them.'"
At this point the light bulb went on over my head - a fluorescent light bulb - and I understood what Marcello was saying: an alternative to frequentism that was even worse than frequentism would have dropped off the radar screens long ago. You can survive by being popular, or by being superior, but alternatives that are neither popular nor superior quickly go extinct.
I can personally testify that Dvorak seems to be much easier on the fingers than Qwerty - but this is not surprising, since if Dvorak really were inferior to Qwerty, it would soon cease to exist. (Yes, I am familiar with the controversy in this area - bear in mind that this is a politically charged topic since it has been used to make accusations of market failure. Nonetheless, my fingers now sweat less, my hands feel less tired, my carpal tunnel syndrome went away, and none of this is surprising because I can feel my fingers traveling shorter distances.)
In any case where you've got (1) a popularity effect (it's easier to use something other people are using) and (2) a most dominant alternative, plus a few smaller niche alternatives, then the most dominant alternative will probably be the worst of the lot - or at least strictly superior to none of the others.
Can anyone else think of examples from their experience where there are several major alternatives that you've heard of, and a popularity effect (which may be as simple as journal editors preferring well-known usages), and the most popular alternative seems to be noticeably the worst?
Addendum: Metahacker said of this hypothesis, "It's wrong, but only sometimes." Sounds about right to me.