FWIW...In the late 1940s I listened (was made to sit down and listen) to a SOTA system, Mono of course. It utilized two loudspeakers, positioned just as we do today for stereo.
It also had a phono pickup which used wooden "needles" that had a triangular cross section, and were sharpened using a special clipper.
The main reason to get a Mono cartridge is to get the proper (large) stylus. Many "Mono" cartridges are simply stereo models with a jumper to eliminate sensitivity to vertical groove modulation. This jumper is in preamps that have a Mono switch.
It also had a phono pickup which used wooden "needles" that had a triangular cross section, and were sharpened using a special clipper.
The main reason to get a Mono cartridge is to get the proper (large) stylus. Many "Mono" cartridges are simply stereo models with a jumper to eliminate sensitivity to vertical groove modulation. This jumper is in preamps that have a Mono switch.