The idea is that duct tape (or the banana peel) applied tightly eliminates airflow to the wart, and the skin gets all wet and weird and wrinkly and pruney there, and your immune system somehow detects that as a threat. So it sends in the self-defense mechanisms to seek and destroy the "invader".
Or something like that.....
I can safely say the MQ is a piece of garbage. I bought one and reviewed it here somewhere.
I found an unbranded folded riveted band from Squinky on eBay and it was a lot better.
I'm with you, the first Yukis were the best. Good luck with your search.
Here are an assortment of gen vintage inserts, all faded from decades of outdoor use. The last pic is one that has faded almost not at all. Notice how different the slate/grey/blues look under different light.
+1 DP
My '71 Sea Dweller still wears the original MkIII insert and it's a dark, rich black. My '68 Sub has its original MkIII insert and it's scratched up but has only faded a little, to a dark slate grey.