SOUND MOVIES BEGINNINGS OR JUST AN ACCIDENT?

I am tired of film critics saying that The Jazz Singer (1927) was the turning point in movies. Because Al Jolson spoke "You haven't seen anything yet" in a type movie that Warner Brothers have been doing since 1926 which was having music and sound effects added to their films. If this was a turning point then the other studios would have been building sound stages starting in 1927. But instead the other studios would build one because they believed talking pictures was just a fad.