There was symbian for a time but it wasn't the majority by any strech. Maemo was GTK.
Qt hasn't dropped support for Linux at all. Qt's strong points have always been about embedded and desktop. Mobile was never really that big with Qt beyond some apps with symbian..
Qt still has many people invested in it. There are so many companies with stakes in Qt here is a list: Integrated Computer Solutions, Intel, RIM, Google, Panasonic, Philips, Samsung, Volvo, Seimens, Autodesk, Dreamworks, Lucasfilm, Walt Disney, Wolfram, European space agency, HP, The Foundry, Cadsoft. Lots of free software uses Qt aswell, Virtualbox, VLC, KDE.
Of that list, how many of those use Qt on symbian? I don't think there is even one. Its all Desktop and embedded.
Putting Qt in more market only adds more contributors and is a good thing.