Stamos seemed to be making a point about the progression and resources being spent on security solutions. Firewalls are deterrents, but there seems to be a general consensus that they are not feasible for the future and the closest approximation that can be achieved to a "fully secure" system is by focusing on Applicaiton Security. During the video Stamos admits and an audience member loudly agrees that "we suck at appsec". Firewalls are stupid crap because we suck at appsec. If we didn't suck at appsec firewalls would and should not matter.