How well does it handle having repeating collections, or complex state interactions that something like React can handle beautifully. Or reactivity (for example a feed of live production system information updating a display with lists if controls with buttons and actions that depend on that state)?

If you answer “brilliantly” I am genuinely curious to give it a go!

Delphi is not limited by crappy web limitations so reactivity is a moot point as one can develop whatever one likes with it. Play with FL Studio DAW, that one is written in Delphi, and see if it satisfies your definition of a "feed of live production system information updating a display with lists if controls with buttons and actions that depend on that state".

https://www.image-line.com/

See it in action e.g. here:

https://www.youtube.com/watch?v=gJUmUd4FfeM

Wow I had no idea FL Studio was written in Delphi.

Anyway, I went pretty deep on SwiftUI from the announcement, and started programming with Delphi 7 / Visual Basic 6. While I enjoy SwiftUI, it has some rough edges still, and it's been 3 or 4 years. Hopefully Apple can put things together this year, especially for macOS apps.

I agree that Delphi is leaps and bounds better than the web technology in popular use today, and every reason I've heard for why (increased DPI, variable screen sizes, etc.) are just poor excuses.

The web is where the money was, development approaches forked, and now the worse approach happens to be more popular.

I can't decide whether it's sad or funny what Microsoft is trying to do with Blazor. They solved their Desktop UI problems by offloading them to you with a browser (now you have the problems).

Just to note Reactivity vs. event handling soup and web/desktop are orthogonal.