When I was younger I tried cheap isolation devices and never really noticed any difference outside of using various budget options underneath turntables. I bought some eastern world garbage off Amazon later in life when aesthetics started to mean something to me..as i bought them because I thought they looked cool.
Couple years ago when I had some bookshelves on stands in my living room I could hear some resonances when I turned the volume up. Once I noticed those resonances I couldn't ignore them and I found it to be quite aggravating.
A retail store had sent me something in the mail about a big sale and I saw the Iso-Acoustic pucks. 60 day trial period so I figured what the heck..even though they were much more expensive then anything I had ever considered before.
When I plucked out the little sorbathene balls off the stands and put the pucks between the speakers and the stands I really didn't know what to expect, and I can honestly say I wasn't expecting much. The difference was audible right away. I read were people said they could tell the difference in the bass but for me it was much more in the midrange and overall clarity. I could turn the volume up much higher without the speakers losing any composure. I could see the subtle difference when comparing sweeps on REW but to my ears it was huge.
I now use pucks of various sizes under everything. One of my amps that I have on the floor I put one of those SubDudes under it. I think that's what they are called. My point being is that once a non believer I strongly feel isolation devices can make a difference depending on your situation. Obviously there are better and more expensive (and cheaper) options out there to choose from. I'd say give a well regarded brand a try before saying they don't do anything for electronics and speakers. Especially if you use tube gear. Just my opinion anyway.