I agree and asked an electronics engineer who spent his working life designing analog circuits for a huge U.S. firm, he gave all the facts, figures and more figures etc, most of which went over my head, but his bottom line was they won't do a thing to the standard of gear we buy.
On the other hand I also agree that people that buy them can hear a difference as expectation bias is a real thing, just like a placebo when the person thought it was a real pill. Or to break it down further, when you wash your car it seems to run better, well mine does. ?