Django, bootstrap and a sprinkling of jQuery works really well and results in simple code that can be maintained by a single dev. Bootstrap is only 11 years old. jQuery is 15 years old. Django is 18 years old.
jQuery is used by 94% of the websites that use JavaScript.
None of those are gui toolkits, though. At best, you are pointing to html working rather well at it. Though, that is more force of will from developers, as html was specifically not a front end toolkit at the outset.
There’s another discussion going on about how the older layers of Windows you dig into, the more useful the UI gets, perhaps that’s the narrative they’re thinking of: https://news.ycombinator.com/item?id=34216619
I’m inclined to agree, older UI toolkits could make plenty productive UIs. But they aren’t good at following yearly evolving design fads, and webpages tend to lean heavily toward marketing and appearances over being more utilitarian.
Older toolkits were great at single team creations. This, interestingly, did mean the person making it knew exactly how to use test it.
I question whether the toolkits were actually better, or we just had fewer things to use test? Certainly fewer form factors. Granted, the decision to try and have a single code base for many different resolutions and such is, of course, questionable.
Edit: directly to the point, is it the old toolkits that made better tools? Are those same toolkits used today? Pointing at older tools does not show that the toolkits were better.
Almost all of the apps bundled with macOS are written in Cocoa (some are written in Cocoa Touch, which is itself a nearly 15-year-old framework). And a great deal of excellent third-party apps -- off the top of my head, Transmit, Pixelmator, Day One, the Omni Group apps.
Mail has always felt like garbage to me. Notes, I will have to give a try again. Though, really, the entire "office suites" that everyone makes always feels off to me. I will full cede that that is just preference.
Safari feels off, as well. But I'm pretty firmly in camp firefox.
When I think bundled apps, I think of their notepad equivalent. The finder. The calculator. And... that is about it. I remember trying to make a script once, and that script editor left me very very lost.