The point is that splitting Google Ads business from eg. Google Maps business will make GAds company and GMaps company set up a mutually beneficial business arrangement — not much needs to change there!
The problem with monopolies is that a company like Google, by dominating one space (be it Maps tech or Advertising marketshare), it can use that as a moat to start dominating other areas, even at a loss (which is what it has done starting from Google Search which it never really monetized as a business but instead jumped into advertising even though it was set up because founders hated online ads).
It's tricky to stop this from the get go, because you want to encourage investment into different markets from established companies.
Free markets are known not to be able to stop this, which is why we've got anti-monopoly laws all around the world.
The problem with monopolies is that a company like Google, by dominating one space (be it Maps tech or Advertising marketshare), it can use that as a moat to start dominating other areas, even at a loss (which is what it has done starting from Google Search which it never really monetized as a business but instead jumped into advertising even though it was set up because founders hated online ads).
It's tricky to stop this from the get go, because you want to encourage investment into different markets from established companies.
Free markets are known not to be able to stop this, which is why we've got anti-monopoly laws all around the world.