Yesterday, I read a well-done blog from a writer and social-media consultant named Paul Gillin lamenting the death of BtoB Magazine, which Crain Communications said it is folding into Ad Age as of the first of next year.

What especially caught my eye was this observation:

“The advertising market for business publications is in free fall, and since most of the magazine’s advertisers are themselves B2B media companies, BtoB has suffered along with everybody else.”

Being a student of the media industry, I wanted to know why. I have a few theories, and I like to test them out on other smart people. Sometimes they agree, and other times I suspect they think I’m way wrong.

So I wrote a comment to Gillin’s blog that asked him what he thinks is driving that free fall. Specifically, I asked:

• Is it that print advertising has become an inefficient way to deliver brand messages?

• Is it because software products have emerged in the media industry that render third-party suppliers—advertisers—less essential? In other words, is it a case of, ‘we can build, so we don’t need to buy?’

• And also, do we buy less? For example, online, ‘we don’t need a printer in a continuous relationship, we need a Web development firm just once every few years.’

• Is advertising in free fall too because new channels and technologies have emerged—such as Facebook, Google and database-management tools—that allow marketers to more effectively identify and communicate with prospects?

• And if that’s the case, does that mean that the audiences that media companies have traditionally aggregated are less valuable and less compelling to marketers?

I don’t know the answer to these questions. I don’t even know if they’re the right questions to ask. But something is driving the decline in advertising, not just in media on media, not just in b-to-b media, but in many print publications.