Because it doesn't rely on both the user and developers to do some yet to be determined 'right thing' for the CPU to behave in a consistent manner. While you are correct that some people want absolute max performance per watt, I would argue that no one wants a CPU that behaves unpredictably or inconsistently. An option to disable one or more power saving features that result in this issue (assuming that's what the issue is) for those who just need maximum performance could be a desired solution for some. While others, possibly most, would be willing to take a short term performance hit from a stall to maintain the best overall performance per watt characteristics.