> The problem is that many investors apply metrics, like P/E or book value, blindly without understanding the assumptions that must be true for the metric to be a meaningful measure of value. It is even more complicated inasmuch as some companies fall into an ambiguous gray area when it comes to appropriate valuation metrics (I'd argue Apple is one such company).

This is obviously the core of the issue. But you'd be surprised at how often it is that these concepts surrounding P/E are parrotted constantly at many leading financial firms and schools.