Much more too it than mass - much about how the equal and opposite vibrations from the groove/stylus are handles. If they don't leave the vinyl through a well matched interface and then disapated or absorbed, there's a real effect of these vibrations coming back to the stylus and causing smearing or resonances etc.

That effects perception of timing or giving more energy to parts of the spectrum etc etc.

I'm talking platter mats here rather than control systems - that is probably about keeping with design specs..