I have a long history with Swing and as painful as it is to use sometimes (e.g. "There are Swing developers with low pain tolerances?") it's astonishing how productive Swing feels compared to React even so many years later. Maybe I'm just warped but GridBagLayout, while containing a certain base level of frustration, is O(1) for frustration. Whereas CSS are absolutely O(n) or worse. One of the best feelings in the world is replacing a complicated nesting of buggy BorderLayouts et al with one nice (slightly verbose) GridBagLayout that actually works.

In my imaginary company that I own where we all run linux laptops that are managed by puppet or something, I think we might make a strong case for building many internal tools in Swing.

The biggest hurdle I see nowadays to using Swing is all about distribution: both of the jvm and the program. Imo that's really where the web won - certainly not because of its dev productivity. So it's definitely a no-go for your actual software product.... but for internal tools where you have a lot more leverage over the environment, I think it looks extremely attractive.

Regarding JavaFX... Honestly, I really like it. I have a personal project that was originally in Swing and I ported it to JavaFX because HiDPI is in a lot better shape there (though I think Swing has since figured it out?). And it's a lot better in many ways. I love-love-love using SceneBuilder for designing the view layer and the Observable pattern, I think, yields a lot of nice QOL/verbosity-reducing things.

That said, I think it did have a slightly higher O() for frustration than Swing's O(1). And I think the community, as a whole, just understands it less (less prior art etc).

So if someone said "build a usable high-quality GUI asap or you die" to me, I'd go to Swing immediately.