Imagine that you get a letter from a friend. In the middle of the letter is a strange paragraph praising the postal service's new product. You later learn that

Imagine that you get a letter from a friend. In the middle of the letter is a strange paragraph praising the postal service's new product. You later learn that this was inserted by the postal service. I'd argue that both you and your friend have been harmed by this and that the postal service should be punished. Their job is to deliver messages unmodified and uninspected. Here, the friend is a web page and the postal service is the ISP. Same deal. Injecting content into a page defames (and possibly breaks) the site and deceives the requester. (Yes, the site should use HTTPS to prevent this. And you should lock your house's door. But that doesn't excuse dishonest ISPs or burglars who take advantage when you don't.)