Qt is a higher-level application dev framework with UI support (like MFC but cross-platform). We were looking for lower-level constructs - especially in the networking and P2P areas.
Edit: in fact just to highlight how similar it is, the way that QtWebKit works is that it is built on top of these modules in a [hand wavy] similar way that blink is built on top of the chrome development platform (I have hacked on Qt, WebKit, and Chrome).
Qt is a C++ application framework, it has both low- and high-level components, much like e.g. Cocoa.
> We were looking for lower-level constructs - especially in the networking and P2P areas.
Which Qt provides. Qt is modular and Qt has plenty of low- or intermediate-level modules, including extensive networking, storage and concurrency systems. Using Qt does not mandate using Qt's UI components.
(I haven't used Chromium libs and have no opinion about them)
There are a lot of cross-platform base libraries out there, many of them (like Qt, GTK/GLib, and Mozilla's stack) well-documented and well-supported. These systems are meant to be reused; Chrome? Not so much. Besides the buzz factor, why would you want to base a product on Chrome instead of one of the codebases designed to be used that way?