The Clinicians Speak, page-20

"Case studies are literally chosen to publish to demonstrate good outcomes"

I can say categorically that is bunkum. Case studies are often published to warn oher practitioners about dangerous adverse events or how to manage cases that had bad outcomes so they can learn from others mistakes. Sometimes they trigger many comments from other readers with similar experiences or helpful ideas on how to better manage problems. One recent example would be published case reports of eugylycaemic ketoacidosis related to SGLT2 inhibitors and surgery which resulted in a meta-analysis of published data to try and establish the relationship with the drug and advice on how to avoid it.

So no, you are completely wrong if you think that case reports are used that way. However publication biases do occur in trials where there is an important commercial reward from a successful outcome or when the financial survival of a company depends on it.

Perhaps that helps clarify things?