Here’s one of my four core principles for today’s media market: these days, relevance is mandatory.

I’m not talking about some of your content. I’m talking about all of your content.

If you’re not scared yet, you should be.

Yesterday, distribution costs were high, which made information scarce. The only way to distribute information was to spend lots of capital on a printing press or a broadcast tower. The only way to make this investment pay off was to make everyone interested in your content.

But the things that interest everyone, like the workings of government, don’t interest anyone very much. What does interest people a lot? Their pets. Gardening. Figure skating. But each of these only appeals a lot to a few people … and it wasn’t worth distributing content at great expense to a few. There weren’t enough figure skating fans in a single media market to pay for their content.

So publishers focused on things that interested everyone a little bit.

Today, distribution costs are low, which makes information plentiful. But that’s not all: relevant information is now plentiful. There’s now an international market online for the free distribution of figure-skating-related content, and those of us who care about figure skating can finally do what we always wanted: read about figure skating for an hour every day.

Aha! That’s the catch. Information is now plentiful, but time remains scarce. When people prioritize their time, of course they always start by consuming the available information that’s most relevant to them, gradually moving to less and less relevant information.

Here’s what’s new: things that interest everyone a little bit aren’t anywhere near the top of that list any more. Newspapers’ problem, therefore, is not that people have become less interested in City Hall. It’s that we’ve always been interested in lots of things other than City Hall, and now those other, more intense interests can be fed.

I’d love to read about City Hall, but I’ve got no time. I just spent an hour reading about figure skating.

In economic terms, less-relevant information has not fallen in absolute value. But the people who spend time consuming it are facing rising opportunity costs.

Therefore, news startups should pick a niche — a niche that a few people care about quite a lot. Or several niches, if they go together for some reason. But for God’s sake, don’t get caught out in the open, peddling a product that everybody cares about a little bit.

Newspapers already tried it.

The common factor among all profitable journalism startups in the last seven years is not Web distribution, user interaction, worse content, better content, more content, less content, paid content or free content. The common factor is a narrow audience.