Okay, maybe it’s a minor point. And after Jeff Bezos rightfully taunted me on stage (an honor, really!) for something I wrote almost three years ago, I should probably shut up about the Kindle for a while.

But Amazon has just put out another press release talking about how great Kindle sales are without including a single actual sales number. Four years after launching the Kindle, Amazon has still not released one concrete number regarding either how many actual Kindle devices they’ve sold or how many Kindle books they’ve sold. To be clear, I have no doubt the number in both cases is “a bunch.” But I keep thinking back to what Steve Jobs said two years ago: “Usually, if they sell a lot of something, you want to tell everybody.”

We know, for instance, that Apple sold 14.8 million iPads in the last nine months of 2010 (it launched in April of that year) and 23.6 million in the first nine months of 2011. Amazon has never gotten any more specific than some variation of “millions of Kindles have been sold,” a numerical region it first referred to in January 2010. An IDC study in March estimated that Amazon had sold about 6.1 million Kindles in 2010. Is that accurate? Who knows?

Instead, Amazon loves making comparisons between unknown variables. Some of those comparisons are easily misinterpreted, such as when it announced in May that it was selling 105 Kindle ebooks for every 100 printed books — which led some people to write headlines like “About Time: Ebooks Outselling Printed Books.” (They’re not. Amazon has a 15-20 percent share of print book sales, whereas it’s the only vendor for Kindle ebooks. It’s like McDonald’s saying Shamrock Shake sales have passed Chicken McNugget sales — and extrapolating that out to mean that green Irish-themed shakes now outsell chicken in the United States.)

Here are today’s new unknowable comparisons for the new Kindles introduced eight weeks ago:

“Even before the busy holiday shopping weekend, we’d already sold millions of the new Kindle family and Kindle Fire was the bestselling product across all of Amazon.com. Black Friday was the best ever for the Kindle family — customers purchased 4X as many Kindle devices as they did last Black Friday — and last year was a great year,” said Dave Limp, Vice President, Amazon Kindle.

I’m sure it was! And “millions” over a specific, defined time span is an improvement from “millions” over a multi-year period. But would it really kill Amazon to say, directly: “We had a great launch for these new Kindles! We sold [positive integer] of them!” Without hard data, it’s hard for content producers to know how much effort to expend building for the platform.

This is a much bigger issue for news organizations and other periodical publishers than it is for book publishers. If you publish books, of course you need to invest time and energy into being on the Kindle. It’s the biggest game in town in a clear growth market. But the decision isn’t as clear cut for newspapers and magazines, which need to decide whether to put a slice of their development budgets into developing Kindle-specific editions of their publications.

(I’m not talking about Android apps, which the Kindle Fire can run and which have the benefit of also working on Android smartphones and tablets. I’m talking about the Kindle-specific mags and papers that only work on the Kindle platform.)

When a media company is deciding whether or not to build an iPhone app, an iPad app, or an Android app, they have real sales numbers — or, in Android’s case, activation numbers — to use when calculating whether it’s worth investing in the platform. On the Kindle, that’s harder. If sales numbers really are impressive, shout them from the rooftops!