There will always be essential complexity in dealing with the client/server nature of web apps. But there's still a lot of incidental complexity that can be burned off.
From my experience: besides both Win32 and VB being from the same entity (Microsoft), which helps a lot, what we had basically were VB bindings for the underlying Win32 library.
This Rio project seems more analogous to a library that tries to do an abstraction on top of Win32, like wxWidgets or Java's AWT. They work but the end results always seem a bit "off".
And unlike Win32, web technologies are moving targets and any assumptions one makes may be wrong some browser updates down the line... and there's where the nightmare comes
It’s called HTML/CSS/JS.
That is why Flash became so loved by Web designers, allowing them to target a rendering surface, completely bypassing the browser.
Also why we are now having Flash's revenge with WebGL/WebGPU/WebAssembly.
However the "until you have to debug it" still applies, unless you ship the browser with the application, but that isn't something people usually do. /s