From the link you provide:

In 2012, Australian psychologist Gina Perry investigated Milgram's data and writings and concluded that Milgram had manipulated the results, and that there was a "troubling mismatch between (published) descriptions of the experiment and evidence of what actually transpired." She wrote that "only half of the people who undertook the experiment fully believed it was real and of those, 66% disobeyed the experimenter".[26][27] She described her findings as "an unexpected outcome" that "leaves social psychology in a difficult situation."[28]

I mean, maybe it shouldn't have been done?

Fuck off with your greater good spiel.

There are very good reasons why our modern code of ethics exist in the first place. We as researchers are not there to do harm but instead to try to uplift the people we work with in the process. We are not there to extract information, but to work with people to help better understand how to improve their lives.

The Milgram Experiment while fascinating, is deeply unethical in its own right and should not be used as an example of anything other than the damage that is cause by conducting an unethical study. That study alone has cause many would be participants to walk away because how can they be trusted with a new study. The experiment was not stopped by the researchers when it was clear the participants were under high pressure and showing visible signs of stress. This is not an extractive field like you imply, it is a morally bankrupt philosophy to have that mindset.

Compensating participants is a sign of goodwill and shows you value their time and work put in. Does not matter if trauma is brought up or created like with the Milgram Experiment. You do it because it creates goodwill and helps people feel safer in the knowledge that both you and the institution you represent actually care. It is not for debate on what circumstances you offer compensation, you just offer it.

The greater good does not come with predatory extractive experiments but instead with studies that value and care for its participants. It is impossible to know just how many people have been turned away from participating because of studies like the one the article is on, the Milgram Experiment and the Stanford Prison Experiment. What we do know is that they have had an extremely negative effect on the perception of academic research and turn people away.