See https://doc.qt.io/qt-5/qtqml-syntax-directoryimports.html#directory-listing-qmldir-files vs. https://doc.qt.io/qt-5/qtqml-modules-qmldir.html#contents-of-a-module-definition-qmldir-file

Another option would be to simply drop these qmldir files, as they seem (by the docs) only needed when importing a directory from a remote file system, where a prepared manifest by a qmldir file improves things (or when trying to control the public interface of the module in that directory some more).

org/kde/plasma/components/private or QtQuick/Controls/Styles/Plasma/private is also done without a qmldir file.