I don't think the idea that natural immunity was effective was ever seriously put into question, there were, and still are questions about relative effectivenes

I don't think the idea that natural immunity was effective was ever seriously put into question, there were, and still are questions about relative effectiveness compared to vaccines, going one way or another depending on the study. But all that is missing the point. The entire point of vaccines is to get immunity without getting the disease. Then there are politics. Some countries have vaccine mandates, others don't, some countries recognize natural immunity, others don't, and the reasons are not just scientific. This is a scientific article, not an article about politics, and it is about the best way to protect yourself assuming you had the disease.