The idea of Rigid Coupling is a Philosophy for the Mechanical Structure.
I refer to this design as a Hard Coupling, if the Material used to create the coupling has a Stable Property.
There are other philosophies used as Well, that run parallel with he above.
Looking at how TT designs are produced today, there is certainly a deviation from certain philosophies and these are evolving into a Hybrid of the Science used to produce the coupling. A Hard and Soft Coupling are being introduced.
In relation to a Standalone Tonearm Pod, is this not just a Step further from have a Tonearm Mounted on a Sub Chassis and a Bearing Mounted on a Upper Chassis, as seen in TT Designs.
In relation to a Standalone Tonearm Pod, it is not too much different from a Cantilever Armboard used on many modern TT designs.
It does look like there is a major shift to how modern design interprets some of these Philosophies of yesteryear, even though remaining a useful guide for adopting for use today. I follow the Rigid Coupling it suits me, to suggest it is the only method pretty much questions many TT's seen in use, that are proving to be exceptional for their impression that can be made.
Very soon my own Investigation will have been carried out, it is a interest only, not a witch hunt to prove/disprove which is better. 'If' something is discovered that is standout and attractive, then this is most likely the structure to be aspired to.