Native apps are ALWAYS more efficient than a responsive web design or web based app. This is why Facebook themselves even said that they did away with their web app, because native apps were much better.
It doesn't matter if XenForo has a responsive design. The fact is that the youth of today (and all the new generations) are looking for APPS, not websites. I know this is hard to grasp because even I am wondering why, but this is just the trend.