Dave Plummer, a former Microsoft engineer and architect of the original Task Manager, explained the complexities of measuring CPU usage. He noted that the process is not as simple as it seems, as CPU activity can vary across different cores and the timing of measurements can influence results. The Task Manager accounts for various states of CPU activity, including user mode, kernel mode, interrupt time, deferred procedure calls, and idle loops, making the measurement of CPU utilization a complex task rather than a straightforward one.