Phase doesn't really matter much in EE for an isolated sinusoid either. But when you compare the phase of a transmitted signal to a local reference, or you comp

Phase doesn't really matter much in EE for an isolated sinusoid either. But when you compare the phase of a transmitted signal to a local reference, or you compare the phases of the sinusoids in an FFT to one another, or you're trying to synchronize the Texas electrical grid to the rest of the country, phase means a lot. Phases are almost always only useful in a relative sense.