Gunnar Peterson picked up on a post on Ross Anderson's group's Light Blue Touchpaper blog:

Conflict Theory Does the defence of a country or a system depend on the least effort, on the best effort, or on the sum of efforts?

The last is optimal; the first is really awful

Software is a mix: it depends on the worst effort of the least careful programmer, the best effort of the security architect, and the sum of efforts of the testers

Moral: hire fewer better programmers, more testers, top architects

Source: 1 Raindrop

And I really couldn't say more than: I agree!