The publisher of News Corp.'s The Daily said earlier this year that the iPad-only publication might need a few more years to be profitable. Today the company announced it won't get that chance.

Although it has been one of the most-popular and highest-grossing iPad news apps, The Daily was unable to gather enough paying subscribers at 99 cents a week or $39.99 a year to sustain itself.

In a note to staff, The Daily's publisher and editor-in-chief said, "Although we have over 100,000 passionate paying subscribers, unfortunately we have not been able to build a big enough audience fast enough to make our business model work."

News Corp. CEO Rupert Murdoch set a high bar. He said early on that The Daily would be a success “when we are selling millions.” With expenses running at about a half million dollars a week, the publication would have needed near 500,000 subscribers at $3.99 a month or $39.99 a year just to break even. So one big failing was the business model.

News Corp. will shut it down on Dec. 15 and as of this morning the apps are no longer available for download. Some of the approximately 120 employees will be folded into the New York Post staff.

Being the first-of-a-kind is as dangerous as it is exciting in the technology world. With few or no prior examples to learn from, you're left to try stuff and learn the hard way. With the benefit of hindsight, there seem to be at least two other major lessons from The Daily's failure:

1. Audience clarity. It was difficult to grasp who exactly was the intended audience of The Daily. It excelled at interactive elements and visual appeal, but the contents were so sprawling and varied that it was tough to know who this publication was speaking for and to.

2. One platform isn't enough. The Daily was first imagined as the daily news magazine for the iPad era. Going with a tablet-first strategy was a great, ambitious idea.

But going with a tablet-only strategy? In hindsight, questionable.

Research has since shown that tablet owners are "digital omnivores" who consume media seamlessly across tablets, smartphones, PCs and print publications. To serve them news on only one platform is not satisfying.

Contrast that with the new direction in which we see publishers like Quartz and USA Today heading -- optimizing their websites for a tablet-style swipe-and-scroll experience, but still serving readers seamlessly across all platforms.

Murdoch said, via a press release:

From its launch, The Daily was a bold experiment in digital publishing and an amazing vehicle for innovation. Unfortunately, our experience was that we could not find a large enough audience quickly enough to convince us the business model was sustainable in the long-term. Therefore we will take the very best of what we have learned at The Daily and apply it to all our properties.

Journalists outside of News Corp. will be applying those lessons too. Here are some other reactions from media figures:

Related: Murdoch's decision wasn't about the money (Capital New York) | News orgs should focus on reader relationships, not readers' devices, Jeff Jarvis says (The Guardian) | "Someone needed to see whether there was such a thing as tablet-native journalism...The answer, it turns out, is no." (Felix Salmon/Reuters) | 3 Theses About The Daily's Demise (Alexis Madrigal/The Atlantic) | The Daily didn't fail, Murdoch gave up (Jack Shafer/Reuters) | Tablet readers don’t want Interactivity, says Hearst president (Mashable).