And they're working on a mobile style, as I said they would likely do when it first came up. A mobile app would require additional upkeep (Android, iOS and likely Windows Phone 7), and push notifications would require additional resources on the part of forum owners, most of which wouldn't be able to do so.
You're also comparing established, developed solutions to a two year old platform with a limited development team. Sure, Mike and Kier could likely do the mobile apps, but then the development of other things would be halted. They could also hire dedicated developers for the mobile solutions, at a time when they're stuck in lawsuits that will end god knows when.
But lets just throw logic and reason out the window and complain about things not going the way they wish

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