[yellowapple]

"unless you're also going to chastise developers who target only one platform"

Which I tend to do, particularly since that "one platform" is almost always either Windows or macOS, neither of which I use on a daily basis (and neither of which I have any desire to use on a daily basis).

Meanwhile, there's such a thing as cross-platform GUI applications that don't try to fit an entire web browser into them. Especially if your programming language of choice doesn't require precompilation, frameworks/toolkits like Qt and GTK and Tk are perfectly viable for cross-platform development, at least on the desktop (which is usually where folks are using the likes of Electron or CEF anyway). They also tend to perform significantly better and stay much closer to the look-and-feel of the rest of the operating system (no, I don't care if you think you know better than me about my sense of style; if your app doesn't respect the look-and-feel of the rest of my system, then it sticks out like mold on a slice of Wonder Bread).

[Qwertie]

Do you know of any of those cross plaform GUI tools that work in the web browser? Targeting Windows/Mac/Linux is easy but outside of JS I have seen no way that you can write one application that works on Web, Windows/Mac/Linux, Android and iOS

[yellowapple]

I know Qt supports both Android and iOS (and a bunch of other mobile platforms, apparently, like Tizen and Blackberry).

I don't think any of them target HTML/JS, though.