There are two reasons why I would want vendors to continue using vacuum seals. The first is that traditionally we have been using vacuum seal bags to ship drugs in and it seems to have been somewhat effective, at least there have not been a lot of arrests of people getting vacuum sealed shipments. I am not one for tradition, but I am conservative when it comes to security measures, and suddenly completely changing the shipping technique used leaves a bad taste in my mouth. I will need to see some scientific studies or some shit showing that it is safe to use MBB without a vacuum sealed bag before I change my mind regarding vacuum sealing being a requirement. Secondly, vacuum sealed bags to the best of my understanding actually have vacuums in them, as the air has all been sucked out leaving some amount of emptiness. This vacuum should pull scent molecules in, and this must be taken into account in addition to the permeability of the bag. I believe, and correct me with citations if I am wrong, that the vacuum in a sealed bag holds the scent in in addition to the actual material the bag is made out of holding the scent in due to low permeability. We can see that MBB has very low permeability , even lower than traditional vacuum sealed bags, but I don't know how to compare the permeability of a MBB without a vacuum seal to the overall scent holding ability of a vacuum sealed bag that is more permeable. I imagine it is not so simple as merely comparing the MVTR of the two bags, however in cases where a vacuum seal is used in addition to the MBB I do believe at this point that MBB is the superior choice.