I don't think that's really the reason for Electron's popularity. While GTK and Qt are cross-platform, my (limited, to be fair) experience with building for multiple platforms was that it was a huge pain in the ass, and Windows and macOS platform integration often felt clunky and out of place.
The big draw for Electron is that we have way way way more web developers out there these days than native-code desktop UI developers, so it's easy to leverage those people and get results fairly quickly, even if the resulting apps don't really conform to any desktop's standard look-and-feel (which I guess avoids the uncanny valley effect of cross-platform toolkits that try to be native, but fail in subtle and not-so-subtle ways). People can even just (sorta) repackage their existing webapp, and end up with more or less a single code base for all desktop platforms + web.
I do agree with you that most of the desktop platforms are pretty annoying to develop for if you want a solid, stable base, but I don't think that's the prevailing reason for Electron's uptake.
My experience of building an electron application for multiple platforms was similarly painful. When you are writing native specific code, you have to write native specific code regardless of if you use Qt or electron. Something has to interface with the operating system. Either you use someone else's code that is cross platform, or you write your own cross platform code.
It's way easier to develop and customize a user interface with the building blocks found in a browser, rather than doing the same with Gtk or QT. To the extent that those have gotten easier, they are emulating html+js+css.
I'm not sure how they've kept up, as I haven't used Qt in some time, but back in the 4.x days the documentation was absolutely stellar. Extremely thorough and almost every non-trivial feature came with code samples. I couldn't for the life of me understand why anyone was using GTK at the time.
My point is not about lack of usability or documentation. Rather that the nature of HTML+CSS+JS lets you do things you can't do as easily in either GTK or QT. In the latter, yes you can easily achieve a certain kind of UI, but not deviate from it, and even formatting/displaying a significant amount of information that doesn't fit into one of the classic widgets can be a bit of a pain.
That depends a lot on what you're used to. It takes me far less time to implement a custom widget that can format/display a significant amount of information that doesn't fit into one of the classic widgets than it takes me to fiddle with CSS to get it to center things correctly ¯\_(ツ)_/¯.
a big part of why browser engines are so unwieldy is the implied compatibility with every website ever, right?
but the "way way more web developers" you mention are not, at least in the context of electron apps, interested in that feature except tangentially..
so while everyone knows a full web-ready browser engine is impractical to design from scratch, maybe a simplified engine that supports a conservative subset of best-practices web-style design is in order?
There are a bunch of “small subset of HTML” UI toolkits already. The first that comes to mind is Sciter: https://sciter.com/ which bundles QuickJS interpreter, built in support for React-like syntax, and a HTML/CSS like markup and rendering environment. You’ll see on the homepage how it’s used in many products you might have heard of.
The issue here is re-use - Sciter is small and very fast, but won’t run an arbitrary existing web app that targets Chrome. Maybe you could argue for a middler-ground, add more HTML features to Sciter until it can run “most” things… but you’ll end up back to having the whole banana.
That's a really interesting idea, but in practice you might find that the "conservative sunset" ends up being different for every toolkit and developer.
Maybe something a bit opinionated, like a React Native-only runtime, could fit the bill here.
TCL/TK is still both easier than electron and will produce nicer apps. I think the Electron thing is the result of the popularity of web development more than native API failures (other than mobile development being an incredible pain in the ass.)
The big draw for Electron is that we have way way way more web developers out there these days than native-code desktop UI developers, so it's easy to leverage those people and get results fairly quickly, even if the resulting apps don't really conform to any desktop's standard look-and-feel (which I guess avoids the uncanny valley effect of cross-platform toolkits that try to be native, but fail in subtle and not-so-subtle ways). People can even just (sorta) repackage their existing webapp, and end up with more or less a single code base for all desktop platforms + web.
I do agree with you that most of the desktop platforms are pretty annoying to develop for if you want a solid, stable base, but I don't think that's the prevailing reason for Electron's uptake.