"Stereo" and "High Fidelity" or "Ultra-High" fidelity are totally different issues. A high fidelity record may be mono as well. Can you imagine that imaging and the stage can be accomplished through the mono with the great success!
I do collect mono records and know how they worth. A lot of older hifi lovers will tell you that true fidelity is in mono records.
The pressing and mastering technology had been changing throughout the vinyl history along with recording as well.
Whenever the new technology was developed the consumers market have to act accordingly so by acheiving some descent sound from mastering by the mid-50's the "high fidelity" was placed on almost all records since they sounded better than previous ones.
I do collect mono records and know how they worth. A lot of older hifi lovers will tell you that true fidelity is in mono records.
The pressing and mastering technology had been changing throughout the vinyl history along with recording as well.
Whenever the new technology was developed the consumers market have to act accordingly so by acheiving some descent sound from mastering by the mid-50's the "high fidelity" was placed on almost all records since they sounded better than previous ones.