Could you please link to some GUI applications you've built in rust, and/or describe why you added those abstractions and built a browser? This doesn't match my experience.
The way you phrased it, it's not. However if you've used Discord, you know that to render it you're essentially rebuilding a web browser due to the sheer variety of formatting, images, animation, audio, videos, languages, widgets, and whatnot that must all coexist in arbitrary forms in every server/room/forum.