It seems logical to place anti vibration devices under record decks but If companies like ATC and others don't feel the need to place their amp and crossover in a separate boxes might this suggest vibrations are not that much of an issue with regard to electronic components.
I don't blindly subscribe to such views derived from the design philosophy of certain speaker manufacturers such as ATC or Harbeth, or anyone on this forum for that matter. I usually form an opinion or judgment based on my own experience which I can share with other forum members later.
To cut to the chase, based on my recent experience with isolation products, I find them to be beneficial when used on both components and loudspeakers. These vibration devices have brought positive changes when placed under the solid-state amplifiers and DAC in my system. I won't elaborate on the differences although I could detail them here since this thread is suggesting on the insignificance of vibration control for components.
The speakers in my main system are fitted with Isoacosutics Gaia 2 whilst the amps and DAC are supported on a combination of Finite Elemente Cerapuc, Cerabase and Nobsound springs. The FE isolators have been used in the system for almost a decade I think, whereas the Nobsound springs were a recent addition about a month ago. I have to say, the Nobsounds are a revelation as it's the first time in 30 years I can actually tune or alter the sound of an amp, not just any tube amp but solid-state amps by just changing the spring configuration. Again, I won't go into detail here. What I can say is suitable isolation devices with proper set up will likely bring positive gains to the sound of the system. With run-of-the-mill products or an improper set up of such isolation devices, you will either hear a negligible difference or worse sound quality.
FWIW I now consider proper isolation to be indispensable in any good system. I have to admit that I did not try some of the best products in the market such as Townshend. Nevertheless, some of the reasonably priced options will still be able to bring a positive change to the system.
I can see that many folks on this forum do not use isolation devices on components as the gear directly sit on a rack or piece of furniture, or the speakers are spiked or placed directly on the floor or carpet. That's perfectly fine as you will still get great sound quality from the system. However, if anyone desires to achieve more from the system whether it's a higher level of refinement or detail, tighter and more defined bass or a more 3-D or holographic sound etc. a proper implementation of appropriate isolation devices will give you that. I actually find the impact to be quite similar to adding room treatments. If anyone can't do room treatments for any particular reason, some of these isolators may come in handy.