The only way to prove that prefixes don't work is to find a search method where, if you apply the same logic with prefixes, it actually makes things worse. Otherwise, it's doing something right.
Just replace in any prefix-method script the prefix "puzzle" with any prefix, even a random One. And you will see that absolutely nothing changes, you can try it yourself.
If the prefix-method really does work, why does it perform the same way with any prefix instead of the puzzle prefix?