Tonearm mount to the plinth vs arm board vs rotating arm board vs isolated tower

I think that it was Einstein that said  “Does the Station stop at this Train”

Now I know that I’m stretching the point a little but as Atmasphere said, to paraphrase..Relative movement between the arm mount and the platter is a bad thing.  We can have them both move in sync, within reason. 
If you agree with this principle, the arm mounting design options are narrowed considerably.

Thanks for all the information.
 I am considering a direct mount tonearm.
is there a sonic difference between Reed 3p and 2a

Yes.

The mounting of the platter bearing in the plinth will be thus coupled as rigidly as possible to the mounting of the tonearm. If it is not, any vibration at all can be interpreted by the pickup (arm and cartridge) as a coloration.

That's the advice you get from 'amateurs'....🤪
HERE is the 'reality' from Mark Doehmann, responsible for the designs of the Continuum Caliburn and Criterion turntables as well as his own Doehmann Helix 1 and Helix 2 turntables.....all of which are carefully designed with the tonearm mounting bases ISOLATED from the bearing and plinth 👍

I've heard the Doehmann Helix in a system with which I am very familiar.  It indeed seems to be a fabulous turntable, perhaps the best belt-drive I have ever heard.  My friend has since sold it because he needs to downsize and decided to go all digital.  I could have bought it for a "nice" price, but even the nice price was a bit much for my blood.  As to the independent mounting of the tonearm, I don't recall that it was evident.  How did he make it look integrated with the turntable and yet isolate it?  By the way, smart guys (Atma-sphere, Richard, and Mark) can differ in opinion, which does not make the persons on the other side of the argument "amateurs".  If you wanted to make a list of competent designers who line up on one side or the other of this particular proposition, I daresay the "couplers" might have a larger contingent.  But you and I have been over this before, and I have no beef with your preference, nor do I wish to argue about it all over again.  Peace.