Learning the notes in music is SO important. Sure you can learn to play by ear and just copy songs from youtube tutorials, but this will severely limit how far you can go in piano. You might have a couple of quick wins, but then you will hit a plateau and not be able to progress further.
There are exceptions to every rule with this. I’m sure you could google right now some amazing people who play solely by ear, but for the vast majority of the population it is a limiting way to learn...
Imagine your child 1 year from today playing piano! What greater gift can you give your child than the gift of music!