Contributing to the steady drip, drip, drip that are articles and research papers documenting mobile's march to ubiquity comes this report from the Pew Research Center. 

Continued growth in the mobile market? Check. Continued growth of smartphones? Check. Continued growth of Internet and email usage on those devices? Check and check. What may be of new news is that 25% of all smartphone owners use it as their primary device to go on the Internet [emphasis mine]. Put another way, for 1/4 of all smartphone users, there is no mobile Internet; there is only the Internet which they use on their phone. Taking another step, it's quite possible that the only web interaction a person could have with your site is in the context of a mobile device.

 If you’re not baking in a platform-independent approach to your digital production, you’re risking alienation of a growing population.