One of the best uses of footnotes is in Softwar, the book on Ellison & Oracle. There, footnotes are an entertaining editorial compromise: the author refused to give up final approval, but he gave Ellison the right to respond within the book.

Ellison will either expand on - or contradict - the author's points. Easily the most appropriate and defensible use of footnotes I've ever encountered.

Link to book: https://www.amazon.com/dp/B00AK78QVI/