Very true that they go to a personal account but before they ever leave the distributer the contents are well known. That's how the inventory is sold today. There are, or were last time I checked, tens of thousands of e-newsletters in the MINS database. MINS breaks everything down for the agencies to use and the creative gets shoved in the e-newsletters when the deals are made.
Again, see post number 5.
This practice has been around for a good many years and it's a pretty stable and well controlled way to advertise. Contextually relevant ads have been inserted into e-newsletters for at least 5 years. If Google made the same mistakes it did with AdSense and didn't apply what the industry already knows then yes, there would be problems.