I would argue that "more complex applications", when it comes to UI, are an anti-pattern. Use standard widgets, and don't be creative.
Of course "standard widgets" don't really exist anymore because of where UI design has gone, but they did provide a consistency that users could rely on. That is gone now. Buttons don't even look like buttons anymore.
The GUI builder of VB6 fell apart the moment you wanted to do a resizable window. Here "more complex applications" = "window that you can resize or maximize".
VB.NET/WinForms (and competitors like Qt Designer) had a pretty good solution for widget placement on resize, all within the GUI builder. So i don't think this was fatal, if Classic VB had survived a bit longer it likely would have been added too.
(Although to date they don't have a great solution for responsive layouts.)
Of course "standard widgets" don't really exist anymore because of where UI design has gone, but they did provide a consistency that users could rely on. That is gone now. Buttons don't even look like buttons anymore.