Google's ads are the outcome of google's success at capturing attention. They aren't the cause of google capturing attention.

Newspaper's had everyone's attention and then they lost it to a million and one alternatives on the internet.

The phone was a major driver but newspapers had been in structural decline for decades as non internet alternatives for attention grew too. Warren Buffet called it in 1991.

I'm not sure so much online ads per se as the destruction on local buying monopolies on goods to a large degree, general unwillingness to pay for news (more or less related), and, also related, desire to (not) buy content online also related. There was essentially a bundle that supported things like foreign bureaus that largely was dismantled.