with apologies to ESR: "with sharp enough eyes, all bugs are visible."

"the impact [is] negligible as long as you follow basic security practices and can recognize when something looks out of place" is a worthless statement, because the majority of users have repeatedly proven to be unable to do that (hence MacDefender, hence the largest families of malware on Windows being fake AV.)

it also makes it too easy to hand-wave away security threats. you got a trojan on your MacBook? you obviously weren't following basic security practices.