You're looking at this from the wrong angle. I actually did a lot of work for fairly large ad agencies and I still only knew Chiat Day from your list (I did work for them, never heard of the others).
The bottom line is, nobody cares. They care about what you say you've done and what you have actually done, and the passion you bring to your cover letter or whatever. The names on the resume won't mean anything to them.
The bigger problem is you've been stewing in the ad agency world and think other people outside it know wtf it's about.
(Having some of that bg myself, I would be very hesitant to hire someone from an ad agency unless they told me in very clear uncertain terms why and how broken it is. On the flip side, I know way more people at ad agencies who actually ship than I do at any other large organizations.)