it would have been a great language, meanwhile they decided to throw everything out and created a language that it is overcomplex, and it is failing to gain any traction outside iOS / Apple's ecosystem. Basically, if you weren't required to use it, nobody would, which makes it a failure.
SwiftUI, should have been a rendering template/library integrated with UIKit. Also, cleaning up some of the UIKit syntanx and framework (simplifying it), and use SwiftUI as a template for UI, would have been ideal.
SwiftUI instead was pitched as replacement, yet it is not near as capable as UIKit, and it is not feature parity even 7 years later.
Just bad leadership by Apple in this case. (probably many of these decissions were 'promo / resume padding driven' as it happens in many large companies).