Most of these procedures recommended by national guidelines and used by surgeons have insufficient [close to zero] readily available, high quality evidence on their clinical effectiveness, which is mainly because of a lack of definitive trials [most are literally not designed to even try to be definitive]. This forces patients and clinicians to make decisions based solely on observational evidence [educated guessing based on experience]. When randomised controlled trials have been conducted, they sometimes [rarely] support observational evidence and expert opinion, but not universally so [LOL, indeed not].
To be clear, I think this is a good study; I was just amused by the understatements there. Two of the ten surgeries they looked at have never been properly tested at all, and just two of the other eight have actually passed muster: total knee replacement and carpal tunnel decompression are the only reasonably clear winners in the whole lot. And they still have significant caveats, like major complications. Complications that aren’t even all that rare.
It’s now old news that these kinds of surgeries are mostly just based on surgical “common sense,” rather than good evidence, which turns out to be a terrible idea. Many of them don’t work when actually tested. This is a great example of why Dr. Mark Crislip wrote: “The three most dangerous words in medicine are ‘in my experience.’” For more on this topic, see the superb 2016 book, Surgery: The ultimate placebo, by surgeon Ian Harris.