Just my non scientific, simple opinion; those bitches steal aroma.
I had a Boveda Pack in with some Banana Durban autoflower buds I wasn't smoking right away. After a couple months, i decided to cut open the Boveda just to see a) what's in it, and b) if there was any truth to them possibly "robbing terps", and sure as shit, the gel inside the pack had more banana aroma than inside the jar! The buds themselves didn't seem to burn as nicely as the buds from the jar w/o a Boveda in it.
How on Earth did people ever store cannabis before the existence of Boveda. Must have been all boof before 2008.