This comes mostly from a misunderstanding of Martin Luther coupled with a desire to be free from Rome. Luther argued that in all matters on which the Bible does speak it is to be believed over Pope or Council. I am not arguing for or against that assertion I merely stating it as bald fact. However this understanding was never a part of what Luther himself called the “ecstatics” who insisted God Himself would lead them into Scriptural truth. Luther firmly believed in the authority of the Church to teach and guide the belief of the laity, he disagreed however with the Church at THAT time because he felt that Rome had departed from the faith of the Fathers and the Apostles.
Again I do not off this as a for or against argument merely as the reasoning behind the German Reformers complaint against Rome.
However following Luther were people like Calvin and the Anabaptists who insisted that ALL authority and tradition and Church teaching could/should be set aside in favor of private personal interpretation. Which of course is exactly what Cardinal Cajetan warned Luther would happen if he persisted in his course of arguing with Rome.
So following on this history this teaching has been further simplified/corrupted to be “We don’t need any information except the Bible and what we personally think it says to lead us” which is why there are some 3000 Christian denominations and (in Texas at least) twenty different types of Baptist Churches in every city of any size.
So you are correct, the teaching that we only need the Bible to learn about the Bible is not found in the bible, but it did not spring up from nowhere.