Why greater competition is more likely than acquisition for media agencies

Since the recent Accenture acquisitions of Karmarama and SinnerSchrader there has been much speculation as to whether a similar deal might be struck in the media agency sector. After all, media agencies at first glance might seem closer bedfellows to management consultancies than creative agencies; both agency disciplines start from a foundation of insight but like consultancies, media agencies tend to focus more on their product in technology, systems and hard data.
So why have we yet to see a