I saw this article yesterday. I was similarly surprised about the history. I was a bit less surprised about the theory, as I did already know about the costate comonad interpretation, and once you get to that level of abstraction an idea tends to show up in multiple contexts. I was surprised by the breadth of the known instances of the idea, though.

Same here. I always thought of lenses as another "kind" of monad but didn't realise they could be distinct foundational blocks. Dang!