When are babies supposed to stop the repetitive sounds or babble?

My son is almost 1 and his pediatrician said he is no longer suppose to be making mamama or bababa sounds. He makes other sounds as well but she states that this repeating needs to stop?! I’m confused idk how I’m supposed to stop it and I didn’t realize he couldn’t still be doing this.. he turns 1 in February. Anyone know anything about this or input?? I have been considering changing pediatrician but maybe I’m mistaken and she is right