Google isn't an ad-supported business, though. They are an ad business, period. Not many companies have the privilege of being an ad provider, which functions much more like a traditional company.
And there haven't been Internet companies for the last 100 years. 50 years ago switching newspapers would've been a much different thing than switching websites today.
The confusion is that Google has two businesses that are integrated. They have products that are advertising supported and they have an advertising platform available to others.
Google could kill their open AdSense product completely and still make billions dollars selling ads on their products.
And there haven't been Internet companies for the last 100 years. 50 years ago switching newspapers would've been a much different thing than switching websites today.