" That's when ad-blocking went in and it's stayed in."
This is a big problem for advertisers. It takes just one bad apple to persuade a user to take the trouble to learn how to block ads and the easiest form of block is a blanket ban. To make it worse, unblocking is a separate job with no motivation, because no-one has ever thought "This ad-free web page needs slower loading times and intrusive distractions.", so it doesn't happen.
So one bad ad experience means the whole industry gets blocked, forever.