Right???@millercarbon I do talk with the voice of authority fairly often, which probably isn't the best way to present things. But I try to temper that with simply not responding if I have any doubts. FWIW dept.: I own two Triplanars and Triplanar is a 10 minute drive from here. We also make a turntable - the model 208. I've serviced turntables of all types as I put myself through engineering school repairing consumer electronics. So I was expressing the mechanical engineering issues that are common to all turntables.
This issue is not unlike the steering in a car. The car has to keep the wheels on the road at all times, and at the same time you have to be able to steer it. To do this, there can't be any play or flex in any of the steering or suspension components or else the handling can get creepy really fast. In a turntable, there can't be any play between the surface of the platter and the locus in which the cartridge is held. If there is, the stylus will be able to move in a way other than the grooves of the LP dictate (introducing chatter and/or coloration). To this end there can't be slop in the bearings nor flex in the plinth. The arm has to be rigidly coupled to the platter bearing - as rigidly and also as 'dead' as possible (the latter being why damping a plinth affects the sound). Otherwise that would be much like a flexible part in the steering of the car- and would result in the wheels not doing what you want.