QWidget sizeHint() constrained to 2/3 screensize

In QWidgetPrivate::adjustSize() the following lines:
s.setWidth(qMin(s.width(), screen.width()*2/3));
s.setHeight(qMin(s.height(), screen.height()*2/3));

constrain the sizeHint() of any widget to being less than 2/3rds of the available screen space. This is not documented anywhere to explain that this is done, or why. There also should be a way to change this behavior as the sizeHint() should not limited like this automatically.

This should be documented and/or changed.