We can even go one step further and say there can't be an ad attacking your attention when the page itself doesn't exist at all.

The bulk of the internet wouldn't exist if not for ads. Things like youtube almost certainly could not exist, with how expensive it is to store data, provide bandwidth, develop the site itself. It's only thanks to ads that the internet is where it is today.

The fact that ads got us here doesn't mean that we should uncritically accept that business model going forward.

The author said they "decide to direct my attention to this website" and used "attack" because they "didn't agree to getting my attention diverted."

The useful distinction is between the content you came to the website to direct your attention toward, and things that tear your attention away.