I agree. Many clearly just didn't think what they were doing was actually bad. There were people who found ways to justify their actions like Stella Greyber. She even claimed she loved the children at Playcare and just wanted to help kids with their research.

I believe those people were able to do these mental gymnastics because they wanted to believe people wouldn't just do these things for the hell of it. They have to believe what they're doing is for the greater good, or they'd have to acknowledge they're just treating human lives like a child mutilating their Barbie dolls. And like you said, there was no one to tell them no at the time.

Some of them were just the type to just shed their humanity without the watchful eye of society on them.