I think there are a lot of people who believe as you do that a TT has no sound and that it’s just a spinning platter.
Here’s the thing. A TT is a combination of a plinth, a motor/drive system, a bearing, a platter and may or may not include some form is suspension. That tiny little stylus, being dragged through the groove of the record, is prone to all kinds of external disturbances. How all the elements of the turntable work together, will determine what kind, and how great those disturbances are. And seeing as how we are dealing with the tiniest of movements, with the tiniest of electrical signals that are being amplified an insane amount, any tiny disturbance, is going to magnified along with the signal.
An ideal turntable, will have no sound. An ideal turntable will impose no disturbances to the movement of the stylus in the groove. A turntable that imposes no disturbances, is very difficult, and costly to manufacture. A turntable with no sound, will allow the cartridge and tonearm to do their jobs with far greater accuracy. A turntable with no sound will let you hear the music more clearly, with better drive, better attack, channel separation, soundstage etc.
All that to say, turntables have a sound they impose on the signal, regardless of how good the tonearm and cartridge are.