Most companies who want iOS/Android App have already done so. So to increase the use of Xamarin would mean to persuade people with existing Apps to move to Xamarin.
That's why people said it's relavent. (I read it from a website linked from a recent post in TDWTF and that's not my opinion)
That page also suggest Xamarin support iOS API level up to iOS 7 only as why he won't move to Xamarin at that time, but I checked and it apparently already added iOS 9.X API support.