CPM is becoming a less useful way to compare programmatic buying paths.
For example, a $4 CPM open web buy can look cheaper than a $7 managed/bundled buy -- until you account for platform fees, SSP take rates, data, creative, and inventory quality (last one is glossed over too frequently).
Normalize for viewability or (ideally) outcomes, and the economics can look *very* different.
Add dynamic take rates on the supply side, and blended averages may hide more than they reveal.
The more useful comparison for media activation is no longer CPM, it’s the "fully-loaded" cost or eCPM.