Working with high voltages isn't rocket science.
You wouldn't start your motorbike, get up to highway speeds, then step off without expecting something bad to happen.
Actually it is high voltage science. People don't start a motor bike without knowing how to ride one.
It's definitely not existential philosophy such as yours. You appear to believe that a thousand volts behaves like a hundred. You never mentioned capacitors in shut off equipment or what an Arc flash is. Do you know? You didn't say.
It also isn't something to run around shrieking in fear about.
A thousand volts obeys Ohm's Law, just like any other voltage.
Yes, indeed, capacitors in shut off equipment can store a lot of energy------- a very valid point.
I didn't include a warning about that, because the OP was not playing around inside the equipment, which was being used to test other stuff, so I limited my advice to that.
In a career of over forty years working on high powered Broadcast & TV Transmitters, including all the high voltage supplies used in Tube equipment (commonly of the order of 10kV), & the associated 3 phase Mains supply wiring to them, I have never run into a case of Arc Flash.
Yes, it does happen, most often in the the power distribution industry, when people make mistakes, just as motorcycle accidents do, but it does not make basic advice about turning off Mains supplies to equipment invalid.
Actually, people do "start motorbikes without knowing how to ride one".
You can't get dual control motorcycles, so a learner is doing just that, & following the instructions of the person riding alongside them teaching them "to the letter".
If a prospective rider was regaled with all the gruesome details of what could happen in a bike smash, they would never try to learn.