Bear in mind that there are alternatives: JavaFX and Compose for Desktop are the ones I know best. They can be used from high level and popular languages. JavaFX is particularly good for desktop apps and can be compiled down to purely native code that starts as fast as an app written in C++ (likewise for Compose but the experiments with that are newer).
There are some downsides: fewer people know them than with HTML. There are a few tweaks like window styles on macOS it could use to be more modern. On the other hand, it's easy to learn and you benefit from a proper reactively bindable widget library, like table and tree views if you need those. For developer tools such widgets can be useful.
CfD uses Material Design of course, but you can customize it.
Having written desktop apps of varying complexity in all these frameworks, I can't say Electron is clearly superior. It is in some cases (e.g. if I was wanting to write a video conferencing app then it makes sense to re-use Google's investment into Hangouts/Meet for that), but it's also worse in some cases. For instance the multi-process model constantly gets in the way, but you can't disable it as otherwise XSS turns into RCE.
You mean developers who not only know 4-5 different language-runtime-GUI stacks well, but also casually maintains 4-5 different versions of the same app? I don’t think they’re “gone”, I think they spend their time in better ways.
Until liability finally becomes a thing in computing like in other industries, then lets see how much everyone cares.
It is slowly happening, lawsuits against failed consulting projects, returns in digital stores, fixes free of charges due to warranties and security regulations changes,....
Nothing else even comes close, unfortunately.
Maybe someday.