Sigh. If you'd bothered to check the date on the article, you'd see it was written almost a year ago, and before Apple back ported async/await from iOS 15. (Which I quite clearly added to the start of the article.)

As to SwiftUI, yes, if you're willing to write a good portion of your code twice you can most certainly use it. That is, unless you're writing for, say, a major financial platform that's still (today) supporting iOS 12.1 as it's minimum version.

Then you need to make a case to management as to why you want to throw a million or so customers under the bus.

I could go on, but I won't. Apple showed how strongly they feel about async/await with the iOS 13 backport. They don't, however, seem to feel that way about SwiftUI.