From the summary: "This isn't a tremendous deal today, but with how things are going, odds are there will be e-Commerce worked into it, and probably credit card transactions... which worries the bejesus out of me."
From what I understand, having multiple layers of protection is a benefit even if it is internal. This means that an intruder simply cannot bypass one layer and then have access to everything. This is what happened at Target. Someone stole credentials from one of their vendors and was in the network where they proceeded to hack other systems.