Edit: Lastly I am not sure how being able to put your own ads on your own website is bad for consumers. It means that people has to go via Google to put ads on a Google website. How can anyone view that as "anti competitive"? I mean, Google could just create a separate ad service for Youtube, say that Youtube now uses its own service and therefore is not anti competitive. Wouldn't that just circumvent this law completely? Or is the goal to be able to force arbitrary ads on any website?
The timesheets of engineers or digital infrastructure isn't a barrier to making this happen, although it might involve some work for external APIs, authentication and reporting.
Likely the solution would be to spin out a separate service for third party ads and make the main network only run on Google services. But that wouldn't help ad websites in Australia at all. The end result would be that websites would probably have a harder time getting money from Google, which would be good for competing ad tech systems but it wouldn't make more money go to those sites.
Still interesting dynamics though, what might theoretically increase bottom line for one part of the org is probably horrible for another.