It's not a hard and fast rule and it's ok to ignore it when it makes sense. But we also don't mind if your commit message takes longer to write than the code took to change and debug.

A lot of context is assumed in commits, and almost all of it is temporal. Capturing as much of that as possible pays off down the line.

Commit in the article is a good example where the context explains much more than the change.

(On the flip side, the pay off has an expiry date so I'm not extremely fussed when people lax, but it's still good to check in basic assumptions whith your code)