Since a phono cartridge is designed to turn very tiny undulations in a record groove into very tiny electrical impulses, that interface can be distorted by very small variations from optimal performance. And so a better platter bearing will generate less vibration that is picked up by the cartridge. A low torque drive system may be affected by stylus drag, which can vary with the pitch of the music being played (since low frequency grooves have large variation than high frequency.
If there is a theoretically perfect turntable, it is one with a perfect connection between platter and cartridge, which allows zero vibration other than what is generated by the record grooves. It would generate zero vibration out of the motor, the platter bearing, the arm bearing, the arm and the cartridge (other than that generated by the record grooves). It would hold perfect speed, no matter what.
As far as mats, platter materials, or plinth materials, they affect the perfect ideal to the extent they affect platter vibration, which can be transmitted to the cartridge.
Since there is no perfection in the real world, we have tradeoffs. Low torque belt drives exist not because low torque is better, but because the designer felt he could isolate motor vibration better by minimizing the interaction between the motor and the platter.
Then finally we have colorations, some of which may be quite pleasant. Because different materials resonate at different frequencies, and since you can't avoid all resonance completely, some folks seek out the more pleasant
coloration. For example many people change the bodies of a DL-103 cartridge from plastic to wood or aluminum, each of which imparts a slightly different sound.
I hope I'm not the only person who attempts to answer the original post. It's a reasonable and interesting question.
