This is true for all analog -> digital advertising. Digital advertising is so enticing to brands because they can MEASURE how their ads are actually doing. Are people looking at my ad? Are they interacting with it? How long? Are then then going to my site? Are they buying something? Are they coming back later? Did they invite someone else? Did those people come to our site? Did they buy something? On and on and on...
Those are all questions we can answer now with digital advertising. You couldn't do that with "analog" ads in print, on TV or Radio.
So at first companies stopped spending as much, then they realized that their normal ads didn't work, but soon, they started spending much more money on digital because they could maximize their returns now.
So in this case, advertisers might start buying less ads if they see that people are ignoring them and leaving the room. However, advertisers will soon figure out what works and we'll have ads that are better tailored for the experience and will make people actually watch / interact with them. This happened with TV ads too... once DVR's became popular, advertisers created ads just for DVR's.