Well said. The notion that Qt widgets are "finished" was just an aspiration not to spend much more money on it I think; they sort of rowed back on this when it became apparent that Qt Quick isn't always appropriate, but by then it had sort of spread around as a "Qt fact" amongst people who didn't actually use it.
The number of rough edges, missing bits and outright bugs mean that it's certainly not "finished"... just like all software really.
They helped spread the rummor when plenty of new features are QML only, specially when targeting non-desktop devices.
To this day if you want a common file dialog that works properly across all Qt deployment targets, you need to use QML, as the Widgets version is not adaptive and will display a tiny desktop common file dialog on an LCD display, for example.
The number of rough edges, missing bits and outright bugs mean that it's certainly not "finished"... just like all software really.