Dear Lew,
You're misquoting me. I said resonate "differently" not "separately". A subtle distinction but a real one nevertheless.
Do you disagree that tonearms resonate in the manner I described?
I think you're taking an over-simplistic view of the design brief. A tonearm will have a natural level of decoupling (point contact through bearings or a single point bearing). Even if the T/T chassis is heavier than an anvil there is a limit to the extent that such coupling can damp the behaviour of the arm(?)
Look at it another way, if such behaviour did not exist it would be pointless selling clip on dampers for tonearms, or using silicone fluid to help control it even in some of the finest engineered tonearms ;^)
A more graphic example is if you clenched a tuning fork in your fist, vibration would be suppressed. If you hold it in the proscribed manner it will operate but it's important to note that a massive object (you) is nevertheless still gripping a non-massive object (the tuning fork).
I don't know Halcro's outboard system but I haven't condemned any approach in fact I seem to remember endorsing what Ralph said ;^)
Kind regards,