That I don't disagree with. The point remains that the Scripture is given us in its historical and linguistic context, and therefore is nearly incomprehensible without some exegetical tradition. The choice is, whose tradition, that of failed priests Luther and Calvin or that of the fathers of the Church throughout centuries.
Certainly some things need interpretation and tradition is used by all sides. However, for the fundamental basics of things such as the identity of Christ, belief, the idea of sin, the existence of heaven and hell, and the elements of needing salvation etc., I don't think much needs to be explained. I still think a child could only read the Bible and know enough to be a Christian.
I've never thought of Luther and Calvin as "failed priests" before, but I can see how you would see it that way. My guess is that they had much more credibility as heroic whistle-blowers than they otherwise would have, so I thank God they were priests.