Most of what pipe smokers claim to know is subjective.
As I deny that subjectivity and objectivity exist, I can summarize this instead as: much of what we know is lore based on imperfect knowledge of a "representation of a representation."
Some relevant links regarding storing tobacco in Mason jars:
http://pipesmagazine.com/forums/topic/storing-tobacco-in-mason-jars-1
http://pipesmagazine.com/forums/topic/jarring-question
http://pipesmagazine.com/forums/topic/cellaring-tobaccos-best-practices
http://pipesmagazine.com/forums/topic/tobacco-jarring
http://pipesmagazine.com/forums/topic/jarring-flakes
http://pipesmagazine.com/forums/topic/jarring-question-2
http://pipesmagazine.com/forums/topic/jarring-large-quantities
http://pipesmagazine.com/forums/topic/aging-tobacco-6
http://pipesmagazine.com/forums/topic/question-on-jarring
http://pipesmagazine.com/forums/topic/mason-jars-1
http://pipesmagazine.com/forums/topic/how-many-ounces-per-mason-jar
http://pipesmagazine.com/forums/topic/how-tight-do-you-pack-your-jars
http://pipesmagazine.com/forums/topic/cellaring