Why your turntable is mounted on a flexible suspension
Press down gently on the edge of your turntable, the casing not the platter. It gives a little, doesn't it? This shows that under the surface of the turntable, between that and the feet, are springs or a flexible, springy material.
You might also, while you are at it, release the pressure suddenly. The turntable should rise up to its normal height and stay there. If it overshoots, or worse still oscillates, that is not a good sign.
The reason a turntable needs to be suspended in this way is that the stylus is very sensitive to vibrations coming up vertically through the floor. This will, at least, transmit footfall and other floor-borne noise to the stylus, which will then be amplified. (And remember that the necessary RIAA equalization will boost the bass by around 40 dB!).
In the worst case, the sound from the speakers will itself be transmitted through the floor and upwards to the stylus. This will badly color the sound, or even produce feedback.
So you can't do without the suspension then?
Well actually you can - there is a better way. The flexible suspension works by, hopefully, absorbing vibrations. This never works 100% and some energy will still travel through.
But if you mount the turntable rigidly to a very heavy plinth, then the vibrations will not be strong enough to make it move, and no energy will be transmitted.
By 'heavy plinth, I mean a thick slab of granite. Slate will do nicely, marble is rather expensive but don't let me stop you. (If you're a cheapskate, then you won't get cheaper than concrete, kilogram for kilogram).
This solution is excellent for a turntable in a fixed location. You will be surprised how much cleaner the sound can be.
For obvious reasons, it isn't recommended for the gigging DJ!