Credit Mix doesn't change when you close an account

This has always been my understanding, and something that Birdman was always very quick to correct people on whether it be here, on MF or Reddit. People would state that if you close an installment loan and your score drops, it's due to the loss of credit mix. Birdman would always chime in and say no, closed accounts are factored into credit mix just like open ones are (like aging metrics) and that it's the Amounts Owed slice of the Fico pie that changes and why a score drop may be realized. I've continued to correct people on this subject over the years. If you read on MF though under unexpected score changes, it states the following: "Second, closing an account can affect your credit mix. FICO Scores consider the different types of credit accounts being used or reported, including credit cards, retail accounts, and installment loans (like auto loans and mortgage loans). People who demonstrate responsible use of different types of credit are generally considered less risky to lenders." This point seems to counter what I have always believed and what Birdman has always said and wrote in the CSP. Maybe it's the interpretation of the language that I'm struggling with here. Using the term "being reported" could simply mean present on credit reports, which of course a closed loan typically still would be. If for some reason it dropped off early, THAT would impact credit mix. How do you all interpret this and what are your thoughts. Taking a look at the Fico negative reason codes and how we know they shift with the closure of a loan, what is your take on the subject?