Fact or misinformation?

Trust exhibitors lol like they really know what they're talking about. They only know how to exhibit perhaps.

No.

The situation where damage can occur is playing a stereo record with a mono cartridge that has "normal" lateral compliance and little or no vertical compliance.

dave

I was embarrassed for the guy.

Didn't want to challenge him, since it's his setup.

Wasn't even an exotic setup. The "exhibit" was lukewarm and he played the system way too loud to showcase the setup.

I did get to enjoy it on other setups. I got the LP  US cleaned at the Kirmuss booth by Charless Kirmuss. Kind of lengthy process, if you do the steps in his setup.

No, he may be confusing it with surface noise. Early mono pressings were played with 1mil conical stylus while with stereo the stylus used were 0,7mil and played monos fine. You can destroy grooves as @intactaudio said.

A small exception is dirty 78's, where groove width is much greater and a modern stylus will reach the bottom of the groove and not only.

Probably he was refering to that.