KDE was created with open source Qt. As in, the developers that wrote KDE used the LGPL version of Qt.
To repeat myself, “Prohibited Combination” shall mean any effort to use, combine, incorporate, link or integrate Licensed Software with any software created with or incorporating Open Source Qt.
Oh goodness, I'm so sorry you had to repeat yourself.. The reason I started my question by saying "forgive me if I'm missing something obvious" is because I'm no expert on licensing issues and was asking a genuine question.
To repeat myself, “Prohibited Combination” shall mean any effort to use, combine, incorporate, link or integrate Licensed Software with any software created with or incorporating Open Source Qt.