Fact or misinformation?

at the end of the day a cartridge is a compliant lever with a needle and either one or two electro-magnetic coils at the other end (or magnet moving inside a coil).

Mono records only have a single direction of displacement.  Stereo have two.

But either way its a compliant diamond sliding through wiggles. A stereo needle will simply pick up the exact same movement on both channels.

I do not see how this will damage anything.

I admit i've never looked closely at how they align the squiggles

So i find this assertion very unlikely

intact audio makes a reasonable point. I doubt most modern cart's have limited vertical compliance tho.  I think i would be more concerned with the reverse, since in the old days the grooves were cut entirely laterally (well, there was that 45 degrees but the two were out of phase....) so the reverse is more, IMO, likely- except that about 0.01% of us have mono cartridges.

Yes, a buddy of mine does. He also has multiple arms on one table. Wonderfully insane.