[epigramx]

Give an example of software that exists for decades and never had an exploit. You might say basic OS tools. The OS might not be secure then; giving internet terminals to everyone in the world is just a stupid oversight; the best is probably a combination of both having internet when needed but most access to it to be through an extremely thick layer of firewalls (e.g. only system administrators updating stuff should be exposed to the internet for software involving airport security).