It's a bit like seeing someone discussing 'square acres'
square yards, square miles, square metres are fine, but acres already include the squared measure bit.
You're perfectly right that the power calculations are all over the shop with the wandering impedance of a loudspeaker. But people want to see power numbers and they aren't aware of how misleading they can be. Still, it's no excuse for giving the power in wrong units.
The amplifier in my lounge can swing +/-50V and +/-15A... whatever power that means depends on the speaker, also, it depends on the waveshape.
Somewhat dodgy firms exploited all the lack of understanding and we got many forms of peak power IHF etc. This dodgy spec inflation reached its high point in the 'CB burner' amplifiers coming out of Italy in the eighties
David.
Ah, crossed with Craig!