Most of them aren't experts in sociobehavioral psychology who write books on this particular subject.

Lots of people also write books. And the Stanford Prison experiment has received a huge amount of criticism by now, afaik.

Also being famous does not automatically make you an expert.

Edit: googled citation for criticism of the SPE https://pubmed.ncbi.nlm.nih.gov/31380664/

Whether you think the experiment itself was good or bad (Zimbardo recognized its failures and ended it early), the lessons it taught were invaluable and that's why they brought him in as an expert witness for the Abu Ghraib trial. Your suggestion that "lots of people write books" is a silly pooh-poohing in that context, especially considering that Zimbardo was already a Stanford professor by that time in 1971, 50 years ago.

You bring forth one expert to support your claim. I am merely pointing out that there are other experts with differing opinions.

An expert in psychology is basically a modern haruspex.