It's not an attractive scene for GUI developers on Linux. Gnome, Qt, and Electron all have some unappealing aspects. Many people who get the itch to make a Linux GUI app will immediately be discouraged by having to choose between them.
I would use it myself, but a lot of developers don't want to use C++ (too complicated) or Python (too slow, dynamicness becomes unwieldy for large projects). Languages in between - like Swift and C# - are the sweet spot for desktop GUI apps.
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