> Electron does not provide that much more desired features than apps from 25 years ago.
That's true, but advanced GUI features aren't Electron's selling point. It's used because it offers easy portability and the ability to leverage web-dev skills.
SDL is intended for gaming and similar applications, it isn't intended for general purpose GUI development. That's what toolkits like Qt and GTK are for. These toolkits do compete with Electron.
With the disclaimer that I don't know a lot about this: Electron has solid support for both desktop and mobile targets. I don't think Qt's mobile support is as good, but I might be mistaken.
Accessibility would be my immediate thought, although I'm not massively experienced in terms of GUI programming, so I could be off the mark here.
With something like SDL2, I would have to interface with each operating system's accessibility API directly, in such a way that's not easily portable, unless I bring in a separate library. Even something like GTK has this problem on platforms other than Linux. With Electron, I know that my program will be accessible wherever Chromium's rendering of HTML is accessible, which is a lot more places than anything I'm going to be able to bodge together.
That's true, but advanced GUI features aren't Electron's selling point. It's used because it offers easy portability and the ability to leverage web-dev skills.