What "can" be done is kind of irrelevant. What's much more important is what metrics would the default (or lazy as you called it) way of doing things with framework X or Y net. If the defaults are a slow and laggy app then that's what 95% or more of the using apps will be.
Not to mention that desktop UI development is just unpleasant. I say this as someone who would really prefer that not to be true, it's just that in my search I've been disappointed. You choose between a number of imperfect "cross-platform" frameworks (and deal with their licensing), or maintain native code for several platforms. Creating custom "widgets" often requires you to start at the drawing API level and have a deep understanding of the framework.
I am keeping an eye on Avalonia, though. The tooling wasn't quite there yet when I tried it.
:(