Why can't the Newspaper Publishers Association launch its own app aggregator?

Rupert Murdoch wants to launch an app aggregator (aka Project Alesia) in the next month or three. It will feature the best of the day's press, constantly updated, a handy digital cuttings service – and cost maybe £5 a week more than Murdoch's own-label £10 apps. Good idea, bad idea? Not if we can't control what's selected, say other papers. Not if it stunts sales of pure News International apps, say the sages of Wapping. So don't hold your breath, or reach for your credit card But why is Rupert taking the lead here? Why can't the Newspaper Publishers Association launch its own aggregated app? Come to think of it, whatever happened to the idea of building an NPA paywall for all major titles to shelter behind and charge? Coalition Cameron has said that invoking monopoly law against wheezes like this would be daft. The coast is clear. Why on earth sit there cavilling when you could be doing something positive?