There aren't a dozen different languages. I'm not even sure that there's a single one with an attractive story on Windows + macOS + Linux. Gtk doesn't work well on anything other than Linux/Unix (not macOS).
So it's mostly Qt vs Electron. Having to compile different binaries for every Linux distro and version makes Qt a non-starter for most. And if you're going to compile it statically to try to avoid that dynamic linking nightmare, you just added more bloat to your download than Electron.
Qt is hardly a popular toolkit for Windows and macOS apps.
And if I use Electron and React, I get to add native-ish mobile apps for little extra work by using React Native there.
So it's mostly Qt vs Electron. Having to compile different binaries for every Linux distro and version makes Qt a non-starter for most. And if you're going to compile it statically to try to avoid that dynamic linking nightmare, you just added more bloat to your download than Electron.
Qt is hardly a popular toolkit for Windows and macOS apps.
And if I use Electron and React, I get to add native-ish mobile apps for little extra work by using React Native there.