Having entered the Linux GUI space only recently, I don't think GTK has that much of an advantage these days. Qt has excellent language bindings for just about every language (even Rust, despite the apparent incompatibilities when it comes to memory management). QtQuick and QML are easy to work with and can easily be designed using the visual designer tools in Qt Creator.
There are licensing issues with using Qt, though. I'm fine with most of my stuff being licensed GPL but if you want to have any other license on your project, you'll probably have to use something like GTK.
> I'm fine with most of my stuff being licensed GPL but if you want to have any other license on your project, you'll probably have to use something like GTK.
What's wrong with using Qt with LGPL? You can't link your app statically, and you have to publish changes that you make to Qt's source code, if you do, but that's mostly it. That's what I'm using for my app[1].
It's just too bad Gtk devs have been progressively removing keyboard input features from Gtk3 and 4. The idea of Gtk as a generic interface is long dead. These days Gtk really just is whatever GNOME is. Which means things like being able to paste filenames into a file->open dialog (gtkfilechooserwidget.c) have been intentionally broken and left to rot since 2014.
If you want to make an application that uses keyboard input, don't chose Gtk anymore.
Ironic, given that in the dim and distant past (i.e. version 1.2) Gtk's (admittedly butt-ugly) file dialog could be driven very easily from the keyboard, even supported effortless wildcard filtering and shell-style tab completion.
It’s less about languages “mattering” and more about meeting devs where they are. Projects, especially those of a FOSS nature which are often hobbies, are more likely to happen when a dev can write in their preferred language.
