The Minus-K is extremely impressive because it has such a ridiculously low resonant frequency - like 0.5 Hz or less in one of the directions. So it's truly effective at full-range isolation. Watch some videos of it in action; it's like magic. A really good, well-tuned spring suspension is a little higher in resonant frequency, but still very effective. Squishy feet / layers are much less effective at isolating lower bass frequencies, but still have some positive effect here. I think harder layers and platforms are really only effective at the midrange and up - no doubt, there is much good to be done here, but it's limited in range. Adding mass can help but it needs to be added in the right place in the right way, and with enough rigidity to suport it - yada yada. You could actually make things worse in some cases by carelessly adding mass (e.g. heavy turntable atop a cheap tower rack).
Anyways - yeah, the Minus-K "negative stiffness" tech looks super impressive and is on my bucket list to try some day :)
I suppose you could say guys like me with an expensive deck (Master Innovation) and no Minus-K have the audiophile equivalent of a "kick me" sign on our backs lol. I have my Master on a CMS Maxxum rack which is no joke - but still, I think a Minus-K would be best. The SOTAs are simply life on "easy mode" by comparison. Especially the Csomos, which has extra mass in its subchassis. Just really super chill and immune to all the nonsense happening around it (caused by me!).