Debian here, and... yup. It's so weird to realize this. I have lots of browser windows open with lots and lots and lots of tabs open, but the only other app I have open is a Matrix client (which honestly is not that great; Element's web version has more features and better polish), and a terminal. If you can call a terminal a GUI app.
Sure, I do use native apps sometimes. A calculator app, GnuCash, VLC, some others. But they're not open all the time; they're infrequent-use apps. And a lot of my VLC use has been replaced by streaming on the web.
It's incredibly sad.