You essentially outline why it should be broken up.
I'm not convinced making the ad tech sector more competitive would prompt that outcome but, "It would disrupt mature products" isn't a compelling argument to allow the existence of a monopoly.
Google is a monopoly, they exert monopoly power and enjoy monopoly pricing.
I think the more likely outcome would be more dynamic products under smaller bannerheads.
I'm not convinced making the ad tech sector more competitive would prompt that outcome but, "It would disrupt mature products" isn't a compelling argument to allow the existence of a monopoly.
Google is a monopoly, they exert monopoly power and enjoy monopoly pricing.
I think the more likely outcome would be more dynamic products under smaller bannerheads.