Dear Thuchan,
Yes, Micro Seiki knew a thing or two about analogue.
Your SX 8000 had it's motor separated from the plinth/platter and, as you say, the very solid arm boards attached rigidly to the plinth.
This is an example of an understandable use of a plinth........not designed to change the sound of the information extracted from the grooves, but to support the platter bearing and tonearms.
Sort of copied by TW Raven among others? :-)