"you fail to understand" Presumptuous.
"cutting lathes have a 70-80lb flywheel and significantly more drive power than most domestic direct drives".
Correct - the process is controlled by the DIRECT DRIVE motor.
'The dynamics of a cutting lathe and its requirements are quite different to the dynamics of replaying a record'.
It is the same signal - the lathe requires much higher torque to cut the disk – replay is a smaller load – proportionally how much different I don’t know.
"does not mean direct drive is in of itself a bad thing"
What do you mean?
Do you mean direct drive can be good?
Or in K3's case a stunningly spectacular achievement: Michael Fremer tells us so, despite your take down of the man. He is a terrifically fit 74 - his apparent age likely isn't much different to you. Michael reports K3 is a cartridge differentiation champ eg "an utterly natural, transparent, and convincing presentation via the Anna D with airy flute roundness, sparkling, effervescent percussion, and zero overhang."
"blows the chrome doors off the Caliburn" ... Michael Fremer.