Because adding a text is just a imgui::text("abc") function call. And a button is just an if(imgui::button("click me")) do_something() statement. There is no other language involved, no markup, no gui editor. Just direct code and highly hackable to make this extend to unexpected lengths.

Thanks, got it.

To add to this, I find it easier to have a simple while loop that renders the screen, fetching variable data on-the-fly, etc. It is rather pleasing to the eye to understand the layout with IM interfaces, etc.

Comparing this to (something like) WPF, you create XAML files, with either or combination of ViewModels and back-end code to "bind" and can get complicated quickly. I guess the only exception to this is if you have commited to WPF non-stop for many months. However, with IM interfaces, its easy to get going (imo)