WPF has amazing layouts.
CSS is irritating as hell. Even modern CSS, justify-content, justify-items, seriously?
Flex has so many weird edge cases it is overwhelming. I have used flex type systems in other frameworks that worked 10x better, while Flexbox is way better than what existed before on the web, it is still and endless source of frustration.
And yes, Winforms is 100x more productive than HTML. Awhile back I designed a fully functioning UI in Winforms to get an idea what I wanted my website to look like. I hadn't used Winforms in years. Took me less than a day to get a UI up and running with data binding to my backend and all the features implemented.
TWO MONTHS of web dev later I had the same thing working in a browser.
Now the browser was styled, and responsive, sure. But 2 months vs 6 hours. The loss of productivity there is insane.