A lot of this is historical. So some thoughts in no particular order:
Back a decade ago qt wasn't cross platform, gtk was. So when I was on windows I was using pidgin (nee gaim), gimp, scite, Firefox... When I moved to Linux I of course kept using the same.
And back then to do cross platform what you usually did was use a meta toolkit like wxwidgets, which on Linux wrapped gtk. So again that was the cross platform toolkit.
Being in c meant complete bindings for a lot more languages especially with SWIG anything that didn't have the level of support of say python went with gtk bindings.
Until KDE4 qt brought with it a dependency on the entire KDE environment kedit, Kate, kstars, ktypingtutor, a bazillion things. Which always seemed like a lot when you just wanted a PDF viewer or something.
Because of the kparts architecture and just culture in general qt/KDE apps tended to include the kitchen sink Konquerer was the most notorious, but a lot of apps were like that, which felt very fat to a lot of people and not 'unixy' enough.
Back a decade ago qt wasn't cross platform, gtk was. So when I was on windows I was using pidgin (nee gaim), gimp, scite, Firefox... When I moved to Linux I of course kept using the same.
And back then to do cross platform what you usually did was use a meta toolkit like wxwidgets, which on Linux wrapped gtk. So again that was the cross platform toolkit.
Being in c meant complete bindings for a lot more languages especially with SWIG anything that didn't have the level of support of say python went with gtk bindings.
Until KDE4 qt brought with it a dependency on the entire KDE environment kedit, Kate, kstars, ktypingtutor, a bazillion things. Which always seemed like a lot when you just wanted a PDF viewer or something.
Because of the kparts architecture and just culture in general qt/KDE apps tended to include the kitchen sink Konquerer was the most notorious, but a lot of apps were like that, which felt very fat to a lot of people and not 'unixy' enough.