Disclosure: never done any iOS development, only android as a hobby/personal projects. I'll be first to admit I have always hated Java with a passion. So when Kotlin came along I was thrilled. It still piggybacked on the wretched and slow as hell JVM but at least the syntax was pleasant to work with and didn't offer one way to get from A to B which involved 3 abstract classes, 5 factories and two ultra wide monitors to fit your class names. Flutter came out iirc about a year later and I was on a bus going to a friends's house on the other end of the country. I pulled out my laptop and spent the next 4 hours fiddling with it. And even though it was young and far not mature, I have to admit, I enjoyed it and managed to make a fully functioning app in that time. I had fiddled with dart a bit while I was still in university iirc, just because it was a promising alternative to js(which I also hate with a passion). And even with my rusty memories of it, I felt right at home. It is true, flutter gives you a far greater flexibility when you are building a UI than any of the native solutions. But I feel like the author(s) of the article made one fundamental mistake - depending heavily on components developed by other people. The truth is, flutter is a good choice when you want to do a custom UI at a relatively low price(in terms of how much time and effort you need to spend on it, compared to the native solutions). In addition for cross platform development, dart, unlike javascript, is entirely predictable.

BUT! If you are working on a complex application which requires a lot of resources and clever ways to keep a low footprint, you might be better off with the native solutions(even though dart has a very mature ffi). I guess a similar comparison would be something like tinygo and micro python for embedded development - good enough for simple things, but anything beyond that, sack them and stick to C/C++.