My grandson learned to read by the time he was 15 months old, using Your Baby Can Read. When he was two, he could read every word in his vocabulary and some that were not even in his vocabulary, like “Chimpanzee”.
I took him to a little zoo when he was 15 months old and pointed to the pig barn, which was labeled, “Pigs” and he told me what it said. I also tested him with flash cards and he was actually able to read them.
My aunt learned to read at 4 while looking at the book as my grandfather read her stories. They later found she had a genius-level IQ. She used to read calculus books for enjoyment!
Some babies are smarter than others. Also, many young parents cannot actually .... well ... read. So, they haven't a prayer of using the program.