It’s funny, but the false assumption is of course that everyone is doing best practice. Few are, whatever the set of practices.
A separate conversation is what “best” even means. It actually usually means “generally accepted” which brings us back to mediocre again.
But those practices are a good aspiration, a good navigational star, for organisations that are currently crap, which is the majority for most sets of practices I know. They will get you from Shu to Ha, then you can think about outgrowing them and becoming Ri.