This is obviously a very biased article written by a *React* developer. I have been on the both sides of development. I love native development using Swift and Xcode but at the same time I have worked with Ionic Apps. Yes, if you are implementing a native app then you will have to reimplement it again for Android using Java etc.
But that does not mean that the other approach is all rainbows and unicorns. Ionic, although is a good framework makes it impossible to debug the applications. Your only true friend when debugging is Chrome Dev Tools and trust me it does not always help to locate the problems.
For larger Ionic apps you will definitely encounter performance issues including flickering. Also, these frameworks Ionic, React Native are always playing the cat and mouse game. Next year Apple will come out with AR Frameworks and no one knows how much time it will take for Ionic or React Native to implement those features.
Having said that Hybrid applications is definitely on the rise and more and more companies are taking advantage of implementing applications once and running it on multiple platforms. But remember that those companies are not in the business of apps, apps is merely a channel for them.