My son, now a second year law student, learned the same way at about the same age.
The professional educators when he was in elementary education, were negative about the process but he too was the most effective reader in the advanced placement group.
That’s been exactly my experience as well. I was an advanced reader by the time I started kindergarten, and was always excused to do other activities when the other children were going through the reading curriculum. It wasn’t until I was in college that I realized that the vast majority of the population actually hears a little voice in their heads that pronounces the words to them as they read. I still find the whole the concept creepy.