I've been learning a lot about this space lately and figure that some people here may have worked in it. Is what I'm seeing correct?
I think the traditional advertising holding companies are structurally broken. Particularly those that have been unable to make acquisitions of digital agencies. Ad companies have been turned on their head - they were put together in order to provide economies of scale on purchasing for media that gave scale (e.g., TV). Digital is the exact opposite - it is fragmented and targeted. It doesn't lend itself to the way holding companies are set up.
Technological expertise combined with global delivery and creative talent is what matters - not fiefdoms of agencies whose big pitch is creative with the benefit of purchasing at scale. Moreover, digital removes a great deal of inefficiency from the marketplace so the overall ad pie is shrinking.