Acting on the numbers you get is not intrinsically a problem: it's what the action is. Looking at how fast stories, function points or whatever get closed is important for planning what you can get done in a given time, and that can be crucial for project management and managing customer expectations. It's not acquiring the information which is a problem; it's not using the metrics which is the problem. The problem is not understanding what the metric can be used to represent (project velocity), and what it cannot (individual productivity);