The intrusiveness of ads is bad, but the fact that code I don’t want and didn’t explicitly authorize is running on my machine is a massive security hole. Not too long ago hackers infiltrated the ad networks of major newspapers and replaced the ads with propaganda.

We have no idea how many times exploit code has been put on these ad servers. And we’re just supposed to trust a bunch of sysadmins to make sure the javascript that lets them track us hasn’t been replaced with something nefarious?