don@n5110:~$ aptitude why libkf5kcmutils5
i partitionmanager Depends kio
i A kio Recommends systemsettings
i A systemsettings Depends libkf5kcmutils5 (>= 5.98.0~)
Thanks Hendrick! I forgot about aptitude -- I never use it.
OK, this gives me a place to start removals.
EDIT: YES! Using "aptitude why", it only took 2 removals, plus "apt autoremove" to clear out all of the unwanted kde and qml packages. Thank you very much, Hendrick, for reminding me about aptitude.