Meetings are by definition a concession to deficient organization. For one either meets or one works. One cannot do both at the same time.
Context
Drucker made this observation while discussing how effective executives manage their time. He argued that a meeting-heavy schedule signals a failure of organisational design: if people must constantly confer, it means work, information, and authority have not been properly allocated. The truly effective executive, in his view, minimises meetings and concentrates uninterrupted time on substantive work.