A static ad wouldn't be nearly as bad as a "audience-targeted" ad that's dynamically served several seconds after the page loads, reflowing the entire layout and causing page jank.

For example, I know that every issue of the Economist is going to have an ad for a luxury watch I will never buy on the inside cover. I have full-on banner blindness to that. That's impossible on display ads that are dynamically placed right in the middle of the article body.