@drrsutliff Thanks for this. That makes slightly more sense.
I still have trouble to see how such a former can be permanently magnetized with constantly changing voltages going through coils. Doing a voltage sweep IS a demagnetization procedure. So normal use of a cart will constantly demag/degauss any cartridge.
Or is the assumption that the fixed magnets in a MC cart will magnetize the formers? Even then, the constantly changing voltages in the coil will demag/degauss the former. And running massive voltages/currents through the fine wires (18 µm in my Rega Aphelion 2) is certainly not desirable either.
If this is a real issue, I wonder why an engineering-driven company like Rega (vibration measuring machine) is using an iron cross and coil assembly on their flagship cart. They use ceramic bearings, carbon fibre in plinth, W-counterweight, so no strangers to exotic materials.
And I bet there are neither measurements nor audio sample files to support any of this. At least I have not seen any.
Thanks y'all for humoring my curiosity.