Scripture Only is one of the propagations of Martin Luther.
Catholics also believe in Holy Tradition.
Protestants do not call it this "Holy Tradition", but believe that we are to spread the news and Word of Christ to all.
It is the same as I understand it. And it is mandated of us all by Christ Himself to go preach to the world such things.
I'm aware of the Catholic belief in tradition, but I'm also aware that the doctrine of sola scriptura has an adequate foundation in Scripture.