I recently ran into an old friend of mine I hadn't seen in a long time. With two young kids, we got to chatting about when to start swimming lessons. Despite being a swimmer himself, he said "I've been told it's a waste of time getting them in the water until they're 4 or 5 years old."
It sort of shocked me to hear that the thinking from twenty or thirty years ago is still very much in our collective attitudes towards swimming. It's easy to forget that new ways of thinking about learning to swim don't always flow through to the public from a rite of passage that doesn't seem to have changed much from when we were kids ourselves.