RMS Power?

When it comes to watts, there never seems to be enough to satisfy some, regardless of how it's measured.
Ultimately, if you can't stay in the same space with it, it ought to be enough.  Unless you're hooked on the smell of things starting to fry.  Then I'd suggest you might need a therapist instead of more wattage.

Just teasing,  but MHO...;)

In Radiography (x-ray), the characteristics of the beam are controlled by varying the kVp across the x-ray tube and the mA in the filament.
The actual dosage to the patient is really dependant on the mA and kV rms, as is the amount of contrast in the image; analogous to dynamic range in audio.
The kV rms varies greatly with the quality of the power supplied to the input of the transformer and even more with the form of rectification. Since the degree of rectification varies so greatly with various audio technologies from tubes to op amps to class D, maybe RMS is at least as meaningful as peak.

....or maybe radiography and audio have nothing in common and I'm full of s#!t. Happens all the time.

The kV rms varies greatly with the quality of the power supplied to the input of the transformer and even more with the form of rectification.

What is "quality of power"? Do you mean amount?
Is "form of rectification" - full wave or half wave?

Since the degree of rectification varies so greatly with various audio technologies from tubes to op amps to class D, maybe RMS is at least as meaningful as peak.

What is "degree of rectification" and how is it related to op-amps or class of the amplifier? RMS of power does not represent anything useful. Your kVrms * mArms is just power.

...or maybe radiography and audio have nothing in common and I’m full of s#!t.

You’re not. Asking questions is important.

While it's interesting that the term RMS power is a misnomer, it is at least consistent. We are still at least comparing apples to apples. I suspect that's all most consumers care about. As long as I know everyone is using the wrong term in the same way, knowing that one amp is rated at 25 wpc rms and another is rated at 80 wpc rms, that is providing me, the consumer, useful information. 

Zavato, amp is rated 80watt and marked 80watt rms by mistake.  In watt rms it would be 97.6 watt.  Vrms*Irms=Pavg  NOT Prms.