Why would the SEC have prosecuted this case if naked shorting never occurs?
An allegation of naked short selling was brought by the SEC against a broker-dealer in 2021. The broker repeatedly violated Regulation SHO, which requires brokers to mark all sell orders for stocks as either "long," "short" or "short exempt." The broker-dealer in question marked $250 million of short sale orders of a hedge fund as either "long" or "short exempt." https://seekingalpha.com/article/4453048-naked-short-selling
Just because something is illegal doesn't mean it can't exist. We have laws against selling illegal drugs, but it still happens all the time.