It's probably because the majority of 1-3 year pianists aren't interested enough in order to go on a piano forum. It takes time to develop a devotion to the piano?
There are plenty of experience pianists that aren't devoted enough to spend their spare non practice time on a forum..
...I've met teachers who have never heard of the common reference books, and after i mention them they are completely disinterested in them, seeing no value in reading books about their profession. I'm guessing they aren't here either..