While I agree that gtk2 is past its "use by date", thats only because replacements exist, there is nothing wrong with gtk2 in and of itself.
My app is shipped via Debian as a Qt5, users do not have a choice, I personally prefer Qt5 too. But I also distribute pre made packages via github. And users there choose gtk2, three times more downloads than Qt5.
(Interestingly, rpm users seem to prefer Qt6 over Qt5.)
Davo