My personal feelings on children and swim lessons aren't always popular. I strongly believe in respectful parenting and I believe a lot of infant swim lessons cross the boundary I lke to hold for my child's bodily autonomy, meaning they are made to do things against their will. I believe that it is our responsibility as the adult to provide supervision when a young child is around water not the child's responsibility to be able to save themselves.
I live in a beach town where water play is pretty much a necessity during the summer in order to enjoy being outside. I chose to wait until my daughter was old enough to ask for swim lessons and make the choice herself. Before she chose that we did use a flotaion device at times but not everytime she was in water. I have also seen children walk right into the deep end of a pool thinking they would float because all they had experienced of being in the water was done in a flotation device.