It seems that for best performance you could simply look at the chart and choose the fastest model in category why isnt this method a good way to choose a CPU?

CPU is the brain of computer and we know it must work accurately and fast.Not only the speed but it should also give the corect results to make our work easier so if we choose the fastest model in each category of CPU then it will work more faster than we desire.So it is the good method for choosing a CPU.