I completely disagree with the title. The fact that "telephony" can be an app on the phone is a WONDERFUL thing. It means that the author of this article has a choice, as opposed to NOT having a choice.
I've never had a problem with 3rd party dialers on Android. But I can smell a scam and I'm technically literate.
To the best of my knowledge there's never been a major dialler related security mishap. In fact much of the panic about Android's "malware ridden ecosystem" seems overblown. Nobody I know has ever had an issue to the best of my knowledge.
But it's definitely a possibility and it's highly probable that eventually something bad will happen on a large scale without some better controls - albeit hopefully not the type that Apple imposes. Cost vs benefit and all that.