I was negative in my deleted comment, but watched the video anyway (I remember skimming through it back in 2019).

It answers my question only tangentially, because it doesn’t touch state management per se. The key point was, what’s the fuss about React SM and why it must be explicit in it. The video basically says that it is a nonsense which may and should be avoided. I agree, and so still don’t get what ggp is talking about.