Seagrape

I enjoyed reading this thread. I had no idea that there were foods one should NOT can so this has been very enlightening. I have one question and it's about canning bread. Why should bread not be canned? I have canned quick breads by just cooking the bread right in the jars then putting a lid and ring on them. They sealed just fine and tasted good when I opened them months later. What is the danger in canning quick bread this way?