The currents' physical component power theory (CPC-PT) is used here to show the improperness of extrapolating definitions of the power phenomena in sinusoidal conditions to non-sinusoidal settings. We prove, through seven examples, that the fundamentals of circuit theory are sine qua non for assessing: 1) the acceptability of a power theory (PT), 2) the appropriates of power quantities such as the reactive power and 3) the reason PTs fail. We show how the Geometric Algebra-based PT overcomes the contradictions found with the CPC-PT and unveils the reason PTs fail. Finally, we show that once the appropriate definition of the reactive power is obtained, the definition of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$S$</tex> based on the geometric addition of the active and non-active powers is a more reliable that the definition of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$S$</tex> based on the product of the root mean square values of the voltage and the current.